subject:(interstellar medium)

1. Hensley, Brandon Scott. On the Nature of Interstellar Grains .

Degree: PhD, 2015, Princeton University

URL: http://arks.princeton.edu/ark:/88435/dsp0170795b03v

► Whether through absorption, scattering, or emission, the effects of interstellar dust are manifest at nearly all wavelengths of astronomical interest. This dissertation synthesizes observations of… (more)

▼ Whether through absorption, scattering, or emission, the effects of interstellar dust are manifest at nearly all wavelengths of astronomical interest. This dissertation synthesizes observations of the diverse optical phenomenology of interstellar dust to investigate the material composition of interstellar grains and to better understand their electromagnetic properties. Chapter 1 of this dissertation serves as both a theoretical and observational introduction. First, the computation of absorption, scattering, and extinction cross sections for particles of a specified material and shape is discussed. Chapter 1 then details the translation of these cross sections into the consequent observable dust properties for a population of interstellar grains. Finally, the current state of observations that constrain the properties of interstellar dust, focusing on elemental abundances, extinction, polarized extinction, emission, and polarized emission, is reviewed. These observations establish benchmark behavior against which models of interstellar dust can be compared. Chapters 2 and 3 focus on the Anomalous Microwave Emission (AME) and in particular whether this emission is produced by spinning polycyclic aromatic hydrocarbons (PAHs). Chapter 2 combines infrared and radio observations of NGC6946 to investigate the relationship between the AME, far-infrared dust emission, and PAH emission. No link between the AME and PAHs is found. Chapter 3 presents a similar analysis for the Galaxy employing a full-sky AME map derived from component separation of the microwave sky. The AME is found to be tightly correlated with the dust radiance but not with the presence of PAHs. Drawing on the observations presented in Chapter 1, Chapter 4 presents new models of interstellar dust that reproduce simultaneously current observations of dust extinction and emission, both total and polarized. Particular attention is paid to the frequency dependence of the polarized infrared emission, which is found to be compatible with both the presence of ferromagnetic nanoparticles embedded in silicate grains or magnetic dipole emission in large, highly conducting graphitic grains. Chapter 4 concludes by discussing observational predictions of these models and their possible extensions beyond the diffuse interstellar medium. Advisors/Committee Members: Draine, Bruce T (advisor).

Subjects/Keywords: Interstellar Dust; Interstellar Medium

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APA (6^th Edition):

Hensley, B. S. (2015). On the Nature of Interstellar Grains . (Doctoral Dissertation). Princeton University. Retrieved from http://arks.princeton.edu/ark:/88435/dsp0170795b03v

Chicago Manual of Style (16^th Edition):

Hensley, Brandon Scott. “On the Nature of Interstellar Grains .” 2015. Doctoral Dissertation, Princeton University. Accessed March 07, 2021. http://arks.princeton.edu/ark:/88435/dsp0170795b03v.

MLA Handbook (7^th Edition):

Hensley, Brandon Scott. “On the Nature of Interstellar Grains .” 2015. Web. 07 Mar 2021.

Vancouver:

Hensley BS. On the Nature of Interstellar Grains . [Internet] [Doctoral dissertation]. Princeton University; 2015. [cited 2021 Mar 07]. Available from: http://arks.princeton.edu/ark:/88435/dsp0170795b03v.

Council of Science Editors:

Hensley BS. On the Nature of Interstellar Grains . [Doctoral Dissertation]. Princeton University; 2015. Available from: http://arks.princeton.edu/ark:/88435/dsp0170795b03v

UCLA

2. Mills, Elisabeth. A More Extreme View of Molecular Gas in the Center of the Milky Way galaxy.

Degree: Astronomy, 2013, UCLA

URL: http://www.escholarship.org/uc/item/1cb43848

► This thesis examines the molecular gas properties in the central 600 parsecs of the Galaxy (the CMZ). I first present a study of a group… (more)

▼ This thesis examines the molecular gas properties in the central 600 parsecs of the Galaxy (the CMZ). I first present a study of a group of HII regions in the central 10 parsecs embedded within the M-0.02-0.07 cloud, adjacent to the Sgr A East supernova remnant. To better depict the physical relationship between these sources, I use archival VLA observations and Paschen-alpha images from the Hubble Space telescope to determine the extinction toward the HII regions. From the measured extinctions and source morphologies, I determine that three of the HII regions lie on the front side of the cloud and formed in the eastern part of the cloud which is unaffected by the supernova remnant's expansion. The higher extinction of the fourth HII region indicates it is embedded in the supernova-compressed ridge, and though younger than the other HII regions, is still older than the supernova. This work is an important determination of the their line-of-sight placement of these sources which helps to define their interaction and strengthens the case that the supernova did not trigger the formation of the HII regions. I next present results from a project I led to survey a sample of CMZ clouds for hot gas using the Green Bank Telescope. I observe multiple highly-excited lines of ammonia, and detect emission from the (9,9) line of ammonia, (excitation energy = 840 K) in 13 of 17 clouds, many of which have no associated star formation. For the three strongest sources, I derive rotation temperatures of 400-500 K, substantially higher than previous temperatures of 200-300 K measured for these clouds. The widespread detections of gas hotter than 400 K indicates for the first time that his hot gas must be heated by global processes in the CMZ. These extremely high temperatures also suggest that cosmic rays are not responsible for the heating of this gas. I also present a determination of the density of the Circumnuclear disk (CND) in the central two parsecs using multiple transitions of HCN and \hco with the APEX telescope, a 12m ALMA prototype dish. These molecules have critical densities > 10⁷ cm^-3 and directly constrain the existence of high-density gas. The excitation analysis of HCN and HCO+ yields significantly tighter limits on the typical densities in this gas n = 10⁵ -10⁷ cm^-3, however I cannot rule out the possibility that a small number of individual gas clumps are tidally stable or in virial equilibrium. The detection of the v₂=1 vibrationally-excited J=4-3 HCN line also indicates that radiative excitation may play a role in the excitation of HCN in this source, but it is not clear if radiative excitation in the CND is a localized or global phenomenon.Finally, I present a summary of early results from a survey of four molecular cloud complexes in the CMZ , which I led using the new capabilities of the VLA. The goal of this work is to determine the variation in temperature in these clouds on 0.1 pc scales to ultimately identify their heating sources. An unanticipated discovery of this study has been hundreds of weak,…

Subjects/Keywords: Astronomy; Galactic Center; Interstellar Medium

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APA (6^th Edition):

Mills, E. (2013). A More Extreme View of Molecular Gas in the Center of the Milky Way galaxy. (Thesis). UCLA. Retrieved from http://www.escholarship.org/uc/item/1cb43848

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Mills, Elisabeth. “A More Extreme View of Molecular Gas in the Center of the Milky Way galaxy.” 2013. Thesis, UCLA. Accessed March 07, 2021. http://www.escholarship.org/uc/item/1cb43848.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Mills, Elisabeth. “A More Extreme View of Molecular Gas in the Center of the Milky Way galaxy.” 2013. Web. 07 Mar 2021.

Vancouver:

Mills E. A More Extreme View of Molecular Gas in the Center of the Milky Way galaxy. [Internet] [Thesis]. UCLA; 2013. [cited 2021 Mar 07]. Available from: http://www.escholarship.org/uc/item/1cb43848.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mills E. A More Extreme View of Molecular Gas in the Center of the Milky Way galaxy. [Thesis]. UCLA; 2013. Available from: http://www.escholarship.org/uc/item/1cb43848

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Tasmania

3. Brown, C. H I absorption in the fourth galactic quadrant.

Degree: 2015, University of Tasmania

URL: https://eprints.utas.edu.au/22770/1/whole_Brown_Courtney_thesis.pdf

► The position of the Sun, within the Milky Way, prohibits us from observing our Galactic system as a whole. Our knowledge of the structure of… (more)

▼ The position of the Sun, within the Milky Way, prohibits us from observing our Galactic system as a whole. Our knowledge of the structure of our Galaxy has increased dramatically; however, there is still no consensus on many seemingly simple questions. Primarily, How many spiral arms does the Milky Way have?, Where are they? And, What’s on the far side of the Galactic center? Galactic H II regions are the formation sites of massive OB stars. Because the main sequence lifetimes of OB stars are short - only ∼tens of millions of years - they thus reveal the locations of current star formation sites. They are therefore found only in locations of active star formation, primarily the spiral arms; H II regions are therefore the archetypal tracers of Galactic spiral structure. The systemic velocity of each H II region, from an observed radio recombination line (RRL), can be applied to a Galactic rotation model in order to calculate the kinematic distance to the region. In the inner Galaxy, line of sight distances are bi-valued such that a single systemic velocity corresponds to two line of sight distances equidistant to the subcentral (tangent) point. Kinematic Distance Ambiguity Resolutions (KDARs) can be made via an analysis of neutral hydrogen (H I) absorption towards each region. We determine a modification of the terminal-velocity KDAR method which investigates H I absorption in velocity channel intervals, rather than in single channels. In addition, we use H I absorption associated with known Galactic structures (in longitude-velocity space) to provide lower-limits on line of sight distances. In this manner we are able to constrain the line of sight distance to over 200 H II regions; including regions located in the extreme inner Galaxy. We also compile a complete census of HII regions with known RRL velocities, taken from the literature - and the H I emission/absorption spectrum pairs toward them – within the bounds of the Southern Galactic Plane Survey; a total of 252 regions. As the result of this work, the list of known fourth quadrant H II regions for which a KDAR analysis has either been prepared for, or attempted, is now exhausted – comparable to the northern hemisphere at the conclusion of Anderson & Bania (2009). This exhaustion of candidates in the northern hemisphere was overcome through the undertaking of large scale HII region discovery surveys. The results of which more than doubled the number of known HII regions within the surveyed longitude range – reinvigorating HII region kinematic distance studies in the northern hemisphere. Following the candidate selection strategies of the northern surveys, we perform a pilot HII region discovery survey in the southern hemisphere. Using the Australia Telescope Compact Array we confirm 28 H II region candidates as genuine regions for the first time. As a result of these analyses, we have made the largest study of H I absorption towards H II regions in the fourth Galactic quadrant ever performed – as well as providing datasets …

Subjects/Keywords: Galaxy; interstellar medium; star formation

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APA (6^th Edition):

Brown, C. (2015). H I absorption in the fourth galactic quadrant. (Thesis). University of Tasmania. Retrieved from https://eprints.utas.edu.au/22770/1/whole_Brown_Courtney_thesis.pdf

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Brown, C. “H I absorption in the fourth galactic quadrant.” 2015. Thesis, University of Tasmania. Accessed March 07, 2021. https://eprints.utas.edu.au/22770/1/whole_Brown_Courtney_thesis.pdf.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Brown, C. “H I absorption in the fourth galactic quadrant.” 2015. Web. 07 Mar 2021.

Vancouver:

Brown C. H I absorption in the fourth galactic quadrant. [Internet] [Thesis]. University of Tasmania; 2015. [cited 2021 Mar 07]. Available from: https://eprints.utas.edu.au/22770/1/whole_Brown_Courtney_thesis.pdf.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Brown C. H I absorption in the fourth galactic quadrant. [Thesis]. University of Tasmania; 2015. Available from: https://eprints.utas.edu.au/22770/1/whole_Brown_Courtney_thesis.pdf

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

McMaster University

4. Benincasa, Samantha. On the Relationship Between Star Formation and the Interstellar Medium in Numerical Simulations.

Degree: MSc, 2014, McMaster University

URL: http://hdl.handle.net/11375/16516

►

The cycle of star formation is the key to galaxy evolution. Stars form in massive collections of extremely dense cold gas. Stellar feedback will inject… (more)

Subjects/Keywords: interstellar medium; galaxies: evolution

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APA (6^th Edition):

Benincasa, S. (2014). On the Relationship Between Star Formation and the Interstellar Medium in Numerical Simulations. (Masters Thesis). McMaster University. Retrieved from http://hdl.handle.net/11375/16516

Chicago Manual of Style (16^th Edition):

Benincasa, Samantha. “On the Relationship Between Star Formation and the Interstellar Medium in Numerical Simulations.” 2014. Masters Thesis, McMaster University. Accessed March 07, 2021. http://hdl.handle.net/11375/16516.

MLA Handbook (7^th Edition):

Benincasa, Samantha. “On the Relationship Between Star Formation and the Interstellar Medium in Numerical Simulations.” 2014. Web. 07 Mar 2021.

Vancouver:

Benincasa S. On the Relationship Between Star Formation and the Interstellar Medium in Numerical Simulations. [Internet] [Masters thesis]. McMaster University; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/11375/16516.

Council of Science Editors:

Benincasa S. On the Relationship Between Star Formation and the Interstellar Medium in Numerical Simulations. [Masters Thesis]. McMaster University; 2014. Available from: http://hdl.handle.net/11375/16516

University of Illinois – Urbana-Champaign

5. Xue, Rui. The relation between atomic and molecular gas: the Magellanic Clouds and beyond.

Degree: PhD, Astronomy, 2015, University of Illinois – Urbana-Champaign

URL: http://hdl.handle.net/2142/88236

► In this thesis, I employ two different observational techniques, ultraviolet spectroscopy and radio interferometry imaging, to study the atomic and molecular gas relation in the… (more)

▼ In this thesis, I employ two different observational techniques, ultraviolet spectroscopy and radio interferometry imaging, to study the atomic and molecular gas relation in the Large/Small Magellanic Clouds and 43 nearby galaxies. These galaxies demonstrate various galactic environments compared with the Milky Way and provide an ideal sample for testing the cloud-scale and galactic-scale models of the atomic-to-molecular transition and molecular cloud formation. From the absorption line analysis on archival data provided by the Far Ul- traviolet Spectroscopic Explorer, I found the molecular hydrogen absorbers trace the diffuse and translucent cloud components in the Magellanic Clouds. Although the absorbers’ veloc- ities generally agree with the large-scale kinematic structure revealed in HI 21cm emission, their physical properties are distinct from the gas revealed by the molecular gas emission in CO. The observed atomic-to-molecular gas relation derived from the absorbers, together with existing gas cloud models, suggest the possible existence of significant diffuse warm atomic gas along the ultraviolet absorption sight lines. In the second part of the thesis, I use high-resolution CO and HI 21cm observations of 45 nearby galaxies, including the Magel- lanic clouds, to analyze the spatial correlation of the interstellar gas in molecular and atomic phases and old stellar populations. The results suggest strong independent roles for galaxy metallicity and stellar-to-gas ratios in the atomic-to-molecular gas transition and are consis- tent with a self-regulation galaxy model of star formation and interstellar medium evolution. The model and observations highlight the importance of the diffuse atomic gas component in understanding the observed atomic and molecular gas relation at sub-kiloparsec and kilo- parsec scales. I conclude that it is essential to incorporate diffuse cloud components into theoretical models of galaxy ISM evolution and molecular cloud formation because of their important role in the galactic ecosystem. Advisors/Committee Members: Wong, Tony (advisor), ISM (advisor), Wong, Tony (Committee Chair), Chu, You-Hua (committee member), Looney, Leslie W. (committee member), Welty, Daniel (committee member).

Subjects/Keywords: Galaxies; Interstellar Medium (ISM)

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Xue, R. (2015). The relation between atomic and molecular gas: the Magellanic Clouds and beyond. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/88236

Chicago Manual of Style (16^th Edition):

Xue, Rui. “The relation between atomic and molecular gas: the Magellanic Clouds and beyond.” 2015. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed March 07, 2021. http://hdl.handle.net/2142/88236.

MLA Handbook (7^th Edition):

Xue, Rui. “The relation between atomic and molecular gas: the Magellanic Clouds and beyond.” 2015. Web. 07 Mar 2021.

Vancouver:

Xue R. The relation between atomic and molecular gas: the Magellanic Clouds and beyond. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2015. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2142/88236.

Council of Science Editors:

Xue R. The relation between atomic and molecular gas: the Magellanic Clouds and beyond. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2015. Available from: http://hdl.handle.net/2142/88236

Louisiana State University

6. Valencic, Lynne Angela. The extinction properties of reddened Galactic OB sightlines.

Degree: PhD, Physical Sciences and Mathematics, 2003, Louisiana State University

URL: etd-1031103-154611 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3276

► A solid understanding of dust grains and their extinction properties is needed to better remove the effects of extinction from data and to comprehend the… (more)

▼ A solid understanding of dust grains and their extinction properties is needed to better remove the effects of extinction from data and to comprehend the nature of the processes which modify grains. This requires a large sample of Galactic sightlines, extending far beyond the solar neighborhood, sampling not only a large volume of space but also a wide variety of environments. To fulfill this requirement, a database of sightlines toward 426 young, reddened stars was constructed using extinction curves based on IUE spectra. The curves were fit and the Fitzpatrick-Massa (FM) parameters were found. FM parameters allow for a quantitative analysis of curve characteristics. IR photometry was also obtained for these sightlines, and thus R(V) (=A(V)/E(B-V)) was found. Links between the environment and various grain populations responsible for different components of the extinction curve were sought, as were relationships between different FM parameters, especially those which describe the 2175 Angstrom absorption feature (the "bump"). A search for sightlines which cannot be described by the R(V)-dependent extinction law of Cardelli, Clayton, & Mathis (1989; hereafter CCM) was also undertaken. The main results are: (1.) The CCM extinction relation is accurate for the vast majority of Galactic sightlines. Thus, processes which lead to a CCM-like extinction curve dominate the ISM and the grain populations responsible for the extinction are modified efficiently and systematically. (2.) The central wavelength of the bump does not shift, and the bump width is environment-dependent, being narrow along diffuse sightlines and broadening with increasing density. These provide constraints on grain mantle materials. (3.) The Galaxy can support environments that lead to Magellanic Cloud-like extinction; this emphasizes the importance of local environment in determining extinction properties. (4.) Reddened Galactic sightlines which do not adhere to the standard extinction relation tend to be dense and molecule-rich.

Subjects/Keywords: interstellar dust; interstellar medium; interstellar extinction

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APA (6^th Edition):

Valencic, L. A. (2003). The extinction properties of reddened Galactic OB sightlines. (Doctoral Dissertation). Louisiana State University. Retrieved from etd-1031103-154611 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3276

Chicago Manual of Style (16^th Edition):

Valencic, Lynne Angela. “The extinction properties of reddened Galactic OB sightlines.” 2003. Doctoral Dissertation, Louisiana State University. Accessed March 07, 2021. etd-1031103-154611 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3276.

MLA Handbook (7^th Edition):

Valencic, Lynne Angela. “The extinction properties of reddened Galactic OB sightlines.” 2003. Web. 07 Mar 2021.

Vancouver:

Valencic LA. The extinction properties of reddened Galactic OB sightlines. [Internet] [Doctoral dissertation]. Louisiana State University; 2003. [cited 2021 Mar 07]. Available from: etd-1031103-154611 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3276.

Council of Science Editors:

Valencic LA. The extinction properties of reddened Galactic OB sightlines. [Doctoral Dissertation]. Louisiana State University; 2003. Available from: etd-1031103-154611 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3276

Cornell University

7. Shannon, Ryan. Pulsars And Their Environments: The Interactions Between Pulsar Emission, Matter, And Gravitational Waves.

Degree: PhD, Astronomy, 2011, Cornell University

URL: http://hdl.handle.net/1813/33605

► We investigate the interaction between radio pulsars, gravitational waves, warm plasma in the interstellar medium, and gravitationally bound matter, the latter three are liberally defined… (more)

▼ We investigate the interaction between radio pulsars, gravitational waves, warm plasma in the interstellar medium, and gravitationally bound matter, the latter three are liberally defined to comprise part of the pulsar environment. To examine the interactions between pulsars and their environments, we undertook observations at radio and infrared wavelengths which were supplemented by analytical and numerical modeling techniques. We assess the sensitivity of an ensemble of ultra-stable millisecond pulsars (a pulsar timing array) to gravitational waves. We find that there are a number of sources of noise, both intrinsic and extrinsic to the pulsar that limit timing array sensitivity. We show that spin noise in millisecond pulsars is fundamentally similar to that in normal pulsars and is present at levels that limit the sensitivity of a timing array even though it is latent in current timing observations. We identify the presence of broad band pulse jitter in observations of the millisecond pulsar J1713+0747 that limits its timing precision when observed at high signal to noise ratio. The properties of a plausible debris disks around the millisecond pulsar B1937+21 are constrained and in this context pulsars are identified that are more suited to long term precision timing. Through simulation, the levels of most forms of interstellar timing noise are identified. We demonstrate that careful choice of observing strategies and more advanced modeling of pulse times of arrival can reduce markedly improve timing precision. We conclude that observations of more pulsars, observed with higher throughput are required to make a significant detection of gravitational waves. In addition, pulsar emission is studied through the lens of their environments. We use multi-path scattering of pulsar radio emission in the interstellar medium to form an effective interferometer and resolve the emission region of PSR B0834+06. We also test the theory that certain forms of pulsar modulation are caused by in-falling material by constraining the presence of debris disks around four variable pulsars. We conclude that pulsars and their environments are inextricably linked and that detailed study of either necessarily requires intimate understanding of both. Advisors/Committee Members: Cordes, James Martin (chair), Lloyd, James (committee member), Wasserman, Ira M (committee member).

Subjects/Keywords: Radio Pulsars; Gravitational Waves; Interstellar Medium

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APA (6^th Edition):

Shannon, R. (2011). Pulsars And Their Environments: The Interactions Between Pulsar Emission, Matter, And Gravitational Waves. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/33605

Chicago Manual of Style (16^th Edition):

Shannon, Ryan. “Pulsars And Their Environments: The Interactions Between Pulsar Emission, Matter, And Gravitational Waves.” 2011. Doctoral Dissertation, Cornell University. Accessed March 07, 2021. http://hdl.handle.net/1813/33605.

MLA Handbook (7^th Edition):

Shannon, Ryan. “Pulsars And Their Environments: The Interactions Between Pulsar Emission, Matter, And Gravitational Waves.” 2011. Web. 07 Mar 2021.

Vancouver:

Shannon R. Pulsars And Their Environments: The Interactions Between Pulsar Emission, Matter, And Gravitational Waves. [Internet] [Doctoral dissertation]. Cornell University; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/1813/33605.

Council of Science Editors:

Shannon R. Pulsars And Their Environments: The Interactions Between Pulsar Emission, Matter, And Gravitational Waves. [Doctoral Dissertation]. Cornell University; 2011. Available from: http://hdl.handle.net/1813/33605

Univerzitet u Beogradu

8. Onić, Dušan Ž. 1982-. Termalno zračenje ostataka supernovih u radio-području.

Degree: Matematički fakultet, 2014, Univerzitet u Beogradu

URL: https://fedorabg.bg.ac.rs/fedora/get/o:8047/bdef:Content/get

►

Astronomija-Astrofizika / Astronomy-Astrophysics

Evolucija ostataka supernovih vezana je za kretanje jednog, bezsudarnog udarnog talasa, nastalog prilikom prostiranja odbacenog zvezdanog materijala nakon eksplozije supernove, velikom brzinom… (more)

▼

Astronomija-Astrofizika / Astronomy-Astrophysics

Evolucija ostataka supernovih vezana je za kretanje jednog, bezsudarnog udarnog talasa, nastalog prilikom prostiranja odbacenog zvezdanog materijala nakon eksplozije supernove, velikom brzinom kroz med-uzvezdanu sredinu. Teorijska razmatranja udarnih talasa su neophodna radi boljeg razumevanja emisionih maglina i, generalno, procesa u med-uzvezdanoj sredini. U okviru ove disertacije, izmed-u ostalog, predstavljeni su rezultati magnetohidrodinamicke (MHD) teorije udarnih talasa sa posebnim osvrtom na moguca resenja u svetlu modela idealne radijativne MHD za opticki gust slucaj. Specijalno, diskutovana su moguca svojstva udarnih talasa kada je dozvoljen skok adijabatskog indeksa i/ili parametra koji odred-uje odnos gasnog prema ukupnom pritisku. Osnovna hipoteza, razmatrana u okviru ove disertacije, odnosi se na mogucnost znacajnog ucesca termalnog zakocnog zracenja u neprekidnom radio-spektru pojedinih Galaktickih ostataka supernovih. Pozitivan odgovor na ovo pitanje bi mogao predstavljati prirodno objasnjenje blago konveksnih neprekidnih radio-spektara pojedinih Galaktickih ostataka koji se prostiru kroz sredinu koja je nesto gusca od prosecne. U tom smislu je vazno utvrditi postojanje indikatora termalnog ansambla elektrona, na dovoljno niskim temperaturama i dovoljno velikim gustinama, kako bi se zakocno zracenje moglo detektovati u radio-podrucju (blizina, interakcija ili prostiranje ostatka kroz molekulski oblak, prisustvo ohlad-enih elektrona koji su ranije zracili u X-podrucju, u fazama nakon Sedov-Tejlorove, detekcija niskofrekventnog krivljenja radio-spektra usled termalne apsorpcije vezane za sam ostatak, detekcija u H, identikacija radio-rekombinacionih linija vezanih za sam ostatak, itd). Znacajno prisustvo termalne komponente u principu moze objasniti i radiospektralne indekse manje od 0.5 odred-ene kod nekolicine evolutivno starijih ostataka (uglavnom mesane morfologije), koji se sire kroz guscu sredinu. Zapravo, u tom slucaju bi manji spektralni indeksi, pod pretpostavkom prostog stepenog zakona, predstavljali prirodnu manifestaciju znacajnog udela termalnog zakocnog zracenja u neprekidnom radio-spektru ostataka supernovih...

Advisors/Committee Members: Urošević, Dejan, 1970-.

Subjects/Keywords: supernova remnants; interstellar medium; shock waves; magnetohydrodynamics

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APA (6^th Edition):

Onić, D. �. 1. (2014). Termalno zračenje ostataka supernovih u radio-području. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:8047/bdef:Content/get

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Onić, Dušan Ž 1982-. “Termalno zračenje ostataka supernovih u radio-području.” 2014. Thesis, Univerzitet u Beogradu. Accessed March 07, 2021. https://fedorabg.bg.ac.rs/fedora/get/o:8047/bdef:Content/get.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Onić, Dušan Ž 1982-. “Termalno zračenje ostataka supernovih u radio-području.” 2014. Web. 07 Mar 2021.

Vancouver:

Onić D�1. Termalno zračenje ostataka supernovih u radio-području. [Internet] [Thesis]. Univerzitet u Beogradu; 2014. [cited 2021 Mar 07]. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:8047/bdef:Content/get.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Onić D�1. Termalno zračenje ostataka supernovih u radio-području. [Thesis]. Univerzitet u Beogradu; 2014. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:8047/bdef:Content/get

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

9. Nedelchev, Borislav. On the Nature of Sodium Excess in Nearby Galaxies.

Degree: 2017, University of Hertfordshire

URL: http://hdl.handle.net/2299/17714

► The 5890, 5895Å Na D absorption lines are sometimes found to be strongly enhanced in nearby galaxies, compared to what is predicted by the best-fitting… (more)

▼ The 5890, 5895Å Na D absorption lines are sometimes found to be strongly enhanced in nearby galaxies, compared to what is predicted by the best-fitting models for the stellar continuum. The resulting Na D absorption excess could be caused either by intrinsically stronger absorption feature in the stellar continuum, due to stellar-population effects that are unaccounted by current population synthesis models, interstellar absorption or both. Using the sample of Jeong et al. (2013) and modelling the excess Na D absorption by means of physically motivated line-profile we derived the kinematics of such an excess absorption. Further drawing from the properties of the host galaxies we address the origin of such an enhanced Na absorption. In the galaxies, where no ionised-gas emission is detected and no reddening by dust is present, the Na D spectral profile is observed to be broader than the stellar line-of-sight velocity distribution, suggesting that most likely in these galaxies the Na D excess arise from stellar photospheric absorption. Conversely, objects with an Na D excess profile narrower than the stellar photospheric lines and exhibiting some reddening by dust have also a small red shift associated to their kinematics, a behaviour that can be explained in terms of interstellar absorption occurring in dust lanes that are not always perfectly settled. In objects with a strong reddening by dust and ionised-gas emission, indicating the presence of a considerable interstellar medium, we can find Na D excess profiles that are clearly blue-shifted, an indication for outflowing cold-gas. In our sample, we found that the objects, hosting outflows, are most likely generally, showing features of intense star-formation activity, or are with nebular emission, powered by a mix of star-forming and nuclear activity, with the latter sometimes attributed to accretion onto a supermassive black hole. Per se, the presence of an active galactic nucleus was found not to be relevant in driving such outflows.

Subjects/Keywords: galaxies; interstellar medium; Sodium enhanced galaxies

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APA (6^th Edition):

Nedelchev, B. (2017). On the Nature of Sodium Excess in Nearby Galaxies. (Masters Thesis). University of Hertfordshire. Retrieved from http://hdl.handle.net/2299/17714

Chicago Manual of Style (16^th Edition):

Nedelchev, Borislav. “On the Nature of Sodium Excess in Nearby Galaxies.” 2017. Masters Thesis, University of Hertfordshire. Accessed March 07, 2021. http://hdl.handle.net/2299/17714.

MLA Handbook (7^th Edition):

Nedelchev, Borislav. “On the Nature of Sodium Excess in Nearby Galaxies.” 2017. Web. 07 Mar 2021.

Vancouver:

Nedelchev B. On the Nature of Sodium Excess in Nearby Galaxies. [Internet] [Masters thesis]. University of Hertfordshire; 2017. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2299/17714.

Council of Science Editors:

Nedelchev B. On the Nature of Sodium Excess in Nearby Galaxies. [Masters Thesis]. University of Hertfordshire; 2017. Available from: http://hdl.handle.net/2299/17714

University of Hawaii – Manoa

10. Beaumont, Christopher. Morphological diagnostics of star formation in molecular clouds.

Degree: 2016, University of Hawaii – Manoa

URL: http://hdl.handle.net/10125/100667

►

Ph.D. University of Hawaii at Manoa 2013.

Molecular clouds are the birth sites of all star formation in the present-day universe. They represent the initial… (more)

Subjects/Keywords: molecular clouds; star formation; interstellar medium

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APA (6^th Edition):

Beaumont, C. (2016). Morphological diagnostics of star formation in molecular clouds. (Thesis). University of Hawaii – Manoa. Retrieved from http://hdl.handle.net/10125/100667

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Beaumont, Christopher. “Morphological diagnostics of star formation in molecular clouds.” 2016. Thesis, University of Hawaii – Manoa. Accessed March 07, 2021. http://hdl.handle.net/10125/100667.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Beaumont, Christopher. “Morphological diagnostics of star formation in molecular clouds.” 2016. Web. 07 Mar 2021.

Vancouver:

Beaumont C. Morphological diagnostics of star formation in molecular clouds. [Internet] [Thesis]. University of Hawaii – Manoa; 2016. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10125/100667.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Beaumont C. Morphological diagnostics of star formation in molecular clouds. [Thesis]. University of Hawaii – Manoa; 2016. Available from: http://hdl.handle.net/10125/100667

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Arizona

11. Juneau, Stephanie. Connecting Galaxy and Supermassive Black Hole Growth During the Last 8 Billion Years .

Degree: 2011, University of Arizona

URL: http://hdl.handle.net/10150/202989

► It has become increasingly clear that a complete picture of galaxy evolution requires a better understanding of the role of Active Galactic Nuclei (AGN). In… (more)

Subjects/Keywords: interstellar medium; Astronomy; active galaxies; galaxy evolution

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APA (6^th Edition):

Juneau, S. (2011). Connecting Galaxy and Supermassive Black Hole Growth During the Last 8 Billion Years . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/202989

Chicago Manual of Style (16^th Edition):

Juneau, Stephanie. “Connecting Galaxy and Supermassive Black Hole Growth During the Last 8 Billion Years .” 2011. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/202989.

MLA Handbook (7^th Edition):

Juneau, Stephanie. “Connecting Galaxy and Supermassive Black Hole Growth During the Last 8 Billion Years .” 2011. Web. 07 Mar 2021.

Vancouver:

Juneau S. Connecting Galaxy and Supermassive Black Hole Growth During the Last 8 Billion Years . [Internet] [Doctoral dissertation]. University of Arizona; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/202989.

Council of Science Editors:

Juneau S. Connecting Galaxy and Supermassive Black Hole Growth During the Last 8 Billion Years . [Doctoral Dissertation]. University of Arizona; 2011. Available from: http://hdl.handle.net/10150/202989

University of Maryland

12. Jameson, Katherine Esther. Molecular Gas and Star Formation at Low Metallicity in the Magellanic Clouds.

Degree: Astronomy, 2016, University of Maryland

URL: http://hdl.handle.net/1903/18994

► The Magellanic Clouds are two interacting, gas-rich, star-forming, low-mass, nearby satellite galaxies of the Milky Way that afford a unique view of low-metallicty star-forming regions,… (more)

▼ The Magellanic Clouds are two interacting, gas-rich, star-forming, low-mass, nearby satellite galaxies of the Milky Way that afford a unique view of low-metallicty star-forming regions, providing the nearest laboratories to study processes relevant to star formation in the early universe. We use the dust emission from HERITAGE Herschel data to map the molecular gas in the Magellanic Clouds, avoiding the known biases of CO emission as a tracer of H2. On small (~ few pc) scales in the Small Magellanic Cloud (SMC), we study the effect of metallicity on the structure of photodissociation regions in the outskirts of molecular clouds using [CII] and [OI] spectroscopy combined with new ALMA 7-m array maps of 12CO and 13CO. We estimate the total amount of molecular gas using [CII] to trace H2 at low-Av and 12CO to trace H2 at high-Av. We find that most of the molecular gas is traced by [CII] emission and that metallicity only affects the relationship between 12CO emission and molecular gas through changes in Av. Using mid-infrared spectroscopy from Spitzer Space Telescope in the SMC, we model the H2 rotational line emission to estimate temperatures, column densities, and fractions of warm H2 gas (T>100 K). The temperatures and column densities of warm H2 gas are similar to nearby galaxies, but the SMC shows somewhat high fractions of warm H2. The properties of the warm H2 gas indicate that it is located in photodissociation regions that are more extended in the low metallicity environment of the SMC. We use dust-based molecular gas maps data to evaluate molecular depletion time scales as a function of spatial scale. We compare galaxy-scale analytic star formation models to our observations and find that successfully predicting the trends in the low metallicity environment needs the inclusion of a diffuse neutral medium. The analytic models, however, do not capture the scatter observed, which computer simulations suggest is driven primarily by the time-averaging effect of star formation rate tracers. The averaging of the scatter in the molecular gas depletion time as a function of scale size suggests that the drivers of the star formation process in these galaxies operate on large scales. Advisors/Committee Members: Bolatto, Alberto D (advisor).

Subjects/Keywords: Astronomy; Interstellar Medium; Magellanic Clouds; Star Formation

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APA (6^th Edition):

Jameson, K. E. (2016). Molecular Gas and Star Formation at Low Metallicity in the Magellanic Clouds. (Thesis). University of Maryland. Retrieved from http://hdl.handle.net/1903/18994

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Jameson, Katherine Esther. “Molecular Gas and Star Formation at Low Metallicity in the Magellanic Clouds.” 2016. Thesis, University of Maryland. Accessed March 07, 2021. http://hdl.handle.net/1903/18994.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Jameson, Katherine Esther. “Molecular Gas and Star Formation at Low Metallicity in the Magellanic Clouds.” 2016. Web. 07 Mar 2021.

Vancouver:

Jameson KE. Molecular Gas and Star Formation at Low Metallicity in the Magellanic Clouds. [Internet] [Thesis]. University of Maryland; 2016. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/1903/18994.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Jameson KE. Molecular Gas and Star Formation at Low Metallicity in the Magellanic Clouds. [Thesis]. University of Maryland; 2016. Available from: http://hdl.handle.net/1903/18994

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Louisville

13. Burchett, Joseph N. Neutral magnesium as a probe of high column density QSO absorbers.

Degree: MS, 2011, University of Louisville

URL: 10.18297/etd/178 ; https://ir.library.louisville.edu/etd/178

► QSOs, providing distant, luminous sources of radiation, provide a means to detect gas by absorption in the interstellar and intergalactic medium. Of particular interest to… (more)

Subjects/Keywords: Quasar absorbers; Interstellar medium; QSOs; Magnesium

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APA (6^th Edition):

Burchett, J. N. (2011). Neutral magnesium as a probe of high column density QSO absorbers. (Masters Thesis). University of Louisville. Retrieved from 10.18297/etd/178 ; https://ir.library.louisville.edu/etd/178

Chicago Manual of Style (16^th Edition):

Burchett, Joseph N. “Neutral magnesium as a probe of high column density QSO absorbers.” 2011. Masters Thesis, University of Louisville. Accessed March 07, 2021. 10.18297/etd/178 ; https://ir.library.louisville.edu/etd/178.

MLA Handbook (7^th Edition):

Burchett, Joseph N. “Neutral magnesium as a probe of high column density QSO absorbers.” 2011. Web. 07 Mar 2021.

Vancouver:

Burchett JN. Neutral magnesium as a probe of high column density QSO absorbers. [Internet] [Masters thesis]. University of Louisville; 2011. [cited 2021 Mar 07]. Available from: 10.18297/etd/178 ; https://ir.library.louisville.edu/etd/178.

Council of Science Editors:

Burchett JN. Neutral magnesium as a probe of high column density QSO absorbers. [Masters Thesis]. University of Louisville; 2011. Available from: 10.18297/etd/178 ; https://ir.library.louisville.edu/etd/178

University of New South Wales

14. Do Duy, Tho. Study of the silicate mineralogy of embedded young stellar objects and the interstellar medium.

Degree: UNSW, 2018, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/60405 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:52086/SOURCE02?view=true

► There is occasionally an absorption feature around 11μm in the spectra of forming stars and probably ISM sightlines. The carrier is still debated to be… (more)

▼ There is occasionally an absorption feature around 11μm in the spectra of forming stars and probably ISM sightlines. The carrier is still debated to be possibly water ice, polycyclic aromatic hydrocarbons, silicon carbide, carbonates or crystalline silicates all of which have been detected in cosmic dust. In this thesis, we present over 60 new ground-based spectra from 8-13μm of more than 40 objects, including three evolved stars which is considered as dust factories, several embedded young stellar objects in whichdust involve in star formation and planet formation, and several objects whose sightlines intersects with many dense an/or diffuse clouds. Our observations were made with a variety of spectrographs on different telescopes, including Michelle on Gemini North, Michelle on UKIRT, TReCS on Gemini South, TIMMI2 on the ESO 3.6 m telescope and COMICS on Subaru. Most of the spectra are compared with the data obtained with the Infrared Space Observatory (ISO) on these and other targets; they show an inflection around 11μm. We aim to identify the carrier of this feature. By comparing the strength of that feature with those at other wavelengths, we are able to exclude all of the possible carriers above but crystalline silicate. The evidence includes the similarity in shape between the 11μm band profile and the emissivity of crystalline olivine, the correlation between this band and the amorphous silicate band at 9.7μm and the best model fit of the spectra, which determines the mass fraction of rystalline silicates in each object. We propose that crystalline silicates exist in the embedded YSO phase and even in the ISM, which was thought to have amorphous silicates only. This result leads to several implications on the life cycle of silicates in particular and cosmic dust in general. There are probably several possibilities, for instance, the destruction of the ISM silicates is not complete or the crystalline silicates can form in the ISM due to a low-temperature crystallisation process. We also investigate self-absorption in the spectra of an embedded young stellar objects (YSOs) and a post-AGB star using an optically thin models with absorption on the sightline and a modified version of the radiative transfer model by Towers et al. (2009). These models, each of which has its own advantages and disadvantages, not only can reproduce the shapes of the spectra, but also reveal the properties of the dust surrounding the objects such as the composition, temperature and thickness. Advisors/Committee Members: Chris, Wright, Australian Defence Force Academy, UNSW.

Subjects/Keywords: Young stellar object; Silicate; Interstellar medium

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APA (6^th Edition):

Do Duy, T. (2018). Study of the silicate mineralogy of embedded young stellar objects and the interstellar medium. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/60405 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:52086/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Do Duy, Tho. “Study of the silicate mineralogy of embedded young stellar objects and the interstellar medium.” 2018. Doctoral Dissertation, University of New South Wales. Accessed March 07, 2021. http://handle.unsw.edu.au/1959.4/60405 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:52086/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Do Duy, Tho. “Study of the silicate mineralogy of embedded young stellar objects and the interstellar medium.” 2018. Web. 07 Mar 2021.

Vancouver:

Do Duy T. Study of the silicate mineralogy of embedded young stellar objects and the interstellar medium. [Internet] [Doctoral dissertation]. University of New South Wales; 2018. [cited 2021 Mar 07]. Available from: http://handle.unsw.edu.au/1959.4/60405 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:52086/SOURCE02?view=true.

Council of Science Editors:

Do Duy T. Study of the silicate mineralogy of embedded young stellar objects and the interstellar medium. [Doctoral Dissertation]. University of New South Wales; 2018. Available from: http://handle.unsw.edu.au/1959.4/60405 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:52086/SOURCE02?view=true

University of Sydney

15. Herron, Christopher Andrew. Advanced Radio Polarimetric Techniques for the Study of the Magnetised, Turbulent, Interstellar Medium .

Degree: 2017, University of Sydney

URL: http://hdl.handle.net/2123/17781

► Galactic processes, such as the formation of stars and the evolution of the Galactic magnetic field, are dependent on the turbulent motion of magnetised gas… (more)

Subjects/Keywords: Radio; Polarimetric; Magnetised; Turbulent; Interstellar; Medium

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APA (6^th Edition):

Herron, C. A. (2017). Advanced Radio Polarimetric Techniques for the Study of the Magnetised, Turbulent, Interstellar Medium . (Thesis). University of Sydney. Retrieved from http://hdl.handle.net/2123/17781

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Herron, Christopher Andrew. “Advanced Radio Polarimetric Techniques for the Study of the Magnetised, Turbulent, Interstellar Medium .” 2017. Thesis, University of Sydney. Accessed March 07, 2021. http://hdl.handle.net/2123/17781.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Herron, Christopher Andrew. “Advanced Radio Polarimetric Techniques for the Study of the Magnetised, Turbulent, Interstellar Medium .” 2017. Web. 07 Mar 2021.

Vancouver:

Herron CA. Advanced Radio Polarimetric Techniques for the Study of the Magnetised, Turbulent, Interstellar Medium . [Internet] [Thesis]. University of Sydney; 2017. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2123/17781.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Herron CA. Advanced Radio Polarimetric Techniques for the Study of the Magnetised, Turbulent, Interstellar Medium . [Thesis]. University of Sydney; 2017. Available from: http://hdl.handle.net/2123/17781

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Michigan Technological University

16. Robare, Andrew. STUDY OF THE CYGNUS REGION WITH FERMI AND HAWC.

Degree: MS, Department of Physics, 2018, Michigan Technological University

URL: https://digitalcommons.mtu.edu/etdr/618

► The Cygnus Cocoon is an extended source of high-energy gamma-ray emission in the Cygnus region. The gamma-ray emission has been attributed to a volume… (more)

Subjects/Keywords: Stars; Interstellar Medium and the Galaxy

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APA (6^th Edition):

Robare, A. (2018). STUDY OF THE CYGNUS REGION WITH FERMI AND HAWC. (Masters Thesis). Michigan Technological University. Retrieved from https://digitalcommons.mtu.edu/etdr/618

Chicago Manual of Style (16^th Edition):

Robare, Andrew. “STUDY OF THE CYGNUS REGION WITH FERMI AND HAWC.” 2018. Masters Thesis, Michigan Technological University. Accessed March 07, 2021. https://digitalcommons.mtu.edu/etdr/618.

MLA Handbook (7^th Edition):

Robare, Andrew. “STUDY OF THE CYGNUS REGION WITH FERMI AND HAWC.” 2018. Web. 07 Mar 2021.

Vancouver:

Robare A. STUDY OF THE CYGNUS REGION WITH FERMI AND HAWC. [Internet] [Masters thesis]. Michigan Technological University; 2018. [cited 2021 Mar 07]. Available from: https://digitalcommons.mtu.edu/etdr/618.

Council of Science Editors:

Robare A. STUDY OF THE CYGNUS REGION WITH FERMI AND HAWC. [Masters Thesis]. Michigan Technological University; 2018. Available from: https://digitalcommons.mtu.edu/etdr/618

17. Shannon, Matthew. The Spectral Variability of Astronomical PAHs.

Degree: 2016, University of Western Ontario

URL: https://ir.lib.uwo.ca/etd/4008

► Polycyclic aromatic hydrocarbons (PAHs) are highly abundant molecules found throughout the universe. Illuminated by ultraviolet photons, they can emit up to 10% of the total… (more)

Subjects/Keywords: Astrochemistry; interstellar medium; spectroscopy; molecules; dust; lines and bands; Stars, Interstellar Medium and the Galaxy

13 more images…

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APA (6^th Edition):

Shannon, M. (2016). The Spectral Variability of Astronomical PAHs. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/4008

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Shannon, Matthew. “The Spectral Variability of Astronomical PAHs.” 2016. Thesis, University of Western Ontario. Accessed March 07, 2021. https://ir.lib.uwo.ca/etd/4008.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Shannon, Matthew. “The Spectral Variability of Astronomical PAHs.” 2016. Web. 07 Mar 2021.

Vancouver:

Shannon M. The Spectral Variability of Astronomical PAHs. [Internet] [Thesis]. University of Western Ontario; 2016. [cited 2021 Mar 07]. Available from: https://ir.lib.uwo.ca/etd/4008.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Shannon M. The Spectral Variability of Astronomical PAHs. [Thesis]. University of Western Ontario; 2016. Available from: https://ir.lib.uwo.ca/etd/4008

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Georgia

18. Alexander, Marcus. Gaussian deconvolution of 21 cm HI spectra.

Degree: 2014, University of Georgia

URL: http://hdl.handle.net/10724/25113

► This work investigates atomic hydrogen emission line spectra at 1420 MHz from the 100 meter Green Bank Telescope in Green Bank, West Virginia using the… (more)

Subjects/Keywords: Interstellar Medium; atomic hydrogen; Cold Neutral Medium; Warm Neutral Medium; Galactic rotation

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APA (6^th Edition):

Alexander, M. (2014). Gaussian deconvolution of 21 cm HI spectra. (Thesis). University of Georgia. Retrieved from http://hdl.handle.net/10724/25113

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Alexander, Marcus. “Gaussian deconvolution of 21 cm HI spectra.” 2014. Thesis, University of Georgia. Accessed March 07, 2021. http://hdl.handle.net/10724/25113.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Alexander, Marcus. “Gaussian deconvolution of 21 cm HI spectra.” 2014. Web. 07 Mar 2021.

Vancouver:

Alexander M. Gaussian deconvolution of 21 cm HI spectra. [Internet] [Thesis]. University of Georgia; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10724/25113.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Alexander M. Gaussian deconvolution of 21 cm HI spectra. [Thesis]. University of Georgia; 2014. Available from: http://hdl.handle.net/10724/25113

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of New South Wales

19. Lowe, Vicki. The environment of high-mass star formation: A study of the molecular environment within two giant molecular clouds.

Degree: Physics, 2014, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/55033 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:36396/SOURCE02?view=true

► If a giant molecular cloud (GMC) begins with the same molecular abundances throughout, then any changes observed between different clumps within that GMC are due… (more)

▼ If a giant molecular cloud (GMC) begins with the same molecular abundances throughout, then any changes observed between different clumps within that GMC are due to its evolutionary stage. By studying how high-mass stars form from clumps, we are able to identify how they shape and are shaped by their environment.We study two different GMCs: the G333 GMC and cloud C of the Vela Molecular Ridge (VMR-C). For the G333 GMC, we enhanced a 3-mm molecular line survey conducted on the Mopra radio telescope by including ammonia (temperature) observations targeted towards dust clumps with the Tidbinbilla 70-m radio telescope. For the VMR-C GMC, we conducted a 12-mm molecular line survey on the Mopra radio telescope. We detected emission for ammonia, cyanoacetylene, cyanobutadiynene, and the water maser line. We modelled the spectral energy distribution for the five dust clumps identified by the water maser emission. We studied the morphology and turbulent properties of both GMCs using molecular transitions from carbon monoxide and its isotopologues, hydrogen cyanide, hydrogen isocyanide, formylium, and diazenylium.In G333 GMC, we find evidence that the clumps identified by molecular emission are substantial in size. Clumps with star formation signs are generally warmer and have larger turbulent line widths. We find evidence of radially triggered star formation in the G333 GMC: infrared clumps without obvious signs of star formation are found preferentially further away from known sites of star formation.We highlight the differences between star formation in the two GMCs by analysing the probability distribution function (PDF) of the molecular gas. Both GMCs have a hierarchical, turbulence driven component, and a gravitationally bound component; with less gravitationally bound gas in the VMR-C GMC. We trialled a new technique: the PDF analysis of molecular lines and show that it can identify real differences between molecular clouds. Advisors/Committee Members: Cunningham, Maria, Physics, Faculty of Science, UNSW, Rathborne, Jill, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Urquhart, James, Max-Planck-Institut für Radioastronomie (MPIfR).

Subjects/Keywords: Star formation; Millimetre astronomy; Interstellar medium; Interstellar chemistry; Molecular line astronomy; Turbulence; Ammonia; Carbon monoxide

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APA (6^th Edition):

Lowe, V. (2014). The environment of high-mass star formation: A study of the molecular environment within two giant molecular clouds. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/55033 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:36396/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Lowe, Vicki. “The environment of high-mass star formation: A study of the molecular environment within two giant molecular clouds.” 2014. Doctoral Dissertation, University of New South Wales. Accessed March 07, 2021. http://handle.unsw.edu.au/1959.4/55033 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:36396/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Lowe, Vicki. “The environment of high-mass star formation: A study of the molecular environment within two giant molecular clouds.” 2014. Web. 07 Mar 2021.

Vancouver:

Lowe V. The environment of high-mass star formation: A study of the molecular environment within two giant molecular clouds. [Internet] [Doctoral dissertation]. University of New South Wales; 2014. [cited 2021 Mar 07]. Available from: http://handle.unsw.edu.au/1959.4/55033 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:36396/SOURCE02?view=true.

Council of Science Editors:

Lowe V. The environment of high-mass star formation: A study of the molecular environment within two giant molecular clouds. [Doctoral Dissertation]. University of New South Wales; 2014. Available from: http://handle.unsw.edu.au/1959.4/55033 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:36396/SOURCE02?view=true

McMaster University

20. Gatopoulos, Chris. Stellar Feedback in a Vertically-Stratified ISM.

Degree: MSc, 2012, McMaster University

URL: http://hdl.handle.net/11375/12749

►

The effect of stellar feedback on the interstellar medium is investigated using numerical simulation. In particular, the roles of supernova feedback and ionization feedback… (more)

Subjects/Keywords: stellar feedback; interstellar medium; star formation rate; supernova; photoionization; numerical; Stars, Interstellar Medium and the Galaxy; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Gatopoulos, C. (2012). Stellar Feedback in a Vertically-Stratified ISM. (Masters Thesis). McMaster University. Retrieved from http://hdl.handle.net/11375/12749

Chicago Manual of Style (16^th Edition):

Gatopoulos, Chris. “Stellar Feedback in a Vertically-Stratified ISM.” 2012. Masters Thesis, McMaster University. Accessed March 07, 2021. http://hdl.handle.net/11375/12749.

MLA Handbook (7^th Edition):

Gatopoulos, Chris. “Stellar Feedback in a Vertically-Stratified ISM.” 2012. Web. 07 Mar 2021.

Vancouver:

Gatopoulos C. Stellar Feedback in a Vertically-Stratified ISM. [Internet] [Masters thesis]. McMaster University; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/11375/12749.

Council of Science Editors:

Gatopoulos C. Stellar Feedback in a Vertically-Stratified ISM. [Masters Thesis]. McMaster University; 2012. Available from: http://hdl.handle.net/11375/12749

University of Helsinki

21. Väisälä, Miikka. Magnetic Phenomena of the Interstellar Medium in Theory and Observation.

Degree: Department of Physics, Division of Particle Physics and Astrophysics; Aalto University, School of Science, Department of Computer Science, ReSoLVE Centre of Excellence, 2017, University of Helsinki

URL: http://hdl.handle.net/10138/225177

► Magnetic fields and turbulent flows pervade the interstellar medium on all scales. The magnetic turbulence that emerges on the large scales cascades towards the small… (more)

▼ Magnetic fields and turbulent flows pervade the interstellar medium on all scales. The magnetic turbulence that emerges on the large scales cascades towards the small scales where it influences molecular cloud structure, and star formation within the densest and coldest clumps of the clouds. Active star formation results in supernovae, and the supernova-driven turbulence takes part in the galactic dynamo process leading to the inverse cascade of turbulent energy. Such a process is one example of self-organisatory processes in the interstellar medium where order arises from chaos. Supernovae also induce and influence other important processes in the galactic disks, and this thesis examines some of them. Differentially rotating disk systems, such as galaxies, are prone to magnetorotational instability, where weak magnetic fields destabilise the otherwise hydrodynamically stable disk system, and lead to angular momentum transport outwards. However, magnetorotational instability can be quenched or even damped by another source of turbulence such as supernovae. As both magnetorotational instability and supernovae are capable of producing dynamo effects, the galactic large-scale magnetic fields are proposed to arise as an interplay of these two effects. In addition, supernovae are observed to be able to generate and sustain large-scale flows in galaxies through the anisotropic kinetic alpha effect. Thermodynamical effects have a significant influence on the properties of turbulence. Due to baroclinicity, the supernova-driven turbulence is highly vortical in nature. These types of flows produce a narrow, non-Gaussian velocity distribution with extended wings and an exponential magneti field distribution. Such effects should be taken into account when interstellar turbulence is parametrized in the form of initial conditions and forcing functions for the purpose of making smaller scale models of molecular cloud formation. The Gaussianity of the magnetic field fluctuations is a common assumption, for example, when fitting magnetic field models to explain large-scale polarization maps of the interstellar dust, and our results suggest that such assumptions should require more examination. To study these phenomena, a combination of numerical approaches and observational methods are needed. Exploring physics of turbulence requires the tools of high-performance computing and precise, high-order numerical schemes. Because of the rapidly increasing demands of computation, novel approaches have to be investigated. To improve computational efficiency this thesis shows how the sixth-order finite difference method can be accelerated with the help of graphics processing units. The properties of the interstellar medium can be examined best by the emission of atomic/molecular gas and by the emission, absorption and scattering of interstellar dust. Looking at small-scale phenomena, molecular line emission from cold prestellar cores is explored. More large-scale effects are examined with the help of polarized dust emission, by combining…

Subjects/Keywords: Polarization; Magnetohydrodynamics; Interstellar medium; Galactic dynamo; Star formation; GPGPU; Polarization; Magnetohydrodynamics; Interstellar medium; Galactic dynamo; Star formation; GPGPU

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APA (6^th Edition):

Väisälä, M. (2017). Magnetic Phenomena of the Interstellar Medium in Theory and Observation. (Doctoral Dissertation). University of Helsinki. Retrieved from http://hdl.handle.net/10138/225177

Chicago Manual of Style (16^th Edition):

Väisälä, Miikka. “Magnetic Phenomena of the Interstellar Medium in Theory and Observation.” 2017. Doctoral Dissertation, University of Helsinki. Accessed March 07, 2021. http://hdl.handle.net/10138/225177.

MLA Handbook (7^th Edition):

Väisälä, Miikka. “Magnetic Phenomena of the Interstellar Medium in Theory and Observation.” 2017. Web. 07 Mar 2021.

Vancouver:

Väisälä M. Magnetic Phenomena of the Interstellar Medium in Theory and Observation. [Internet] [Doctoral dissertation]. University of Helsinki; 2017. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10138/225177.

Council of Science Editors:

Väisälä M. Magnetic Phenomena of the Interstellar Medium in Theory and Observation. [Doctoral Dissertation]. University of Helsinki; 2017. Available from: http://hdl.handle.net/10138/225177

McMaster University

22. Leigh, William Nathan. The Physics of Mergers: Theoretical and Statistical Techniques Applied to Stellar Mergers in Dense Star Clusters.

Degree: PhD, 2011, McMaster University

URL: http://hdl.handle.net/11375/10571

► In this thesis, we present theoretical and statistical techniques broadly related to systems of dynamically-interacting particles. We apply these techniques to observations of dense… (more)

▼ In this thesis, we present theoretical and statistical techniques broadly related to systems of dynamically-interacting particles. We apply these techniques to observations of dense star clusters in order to study gravitational interactions between stars. These include both long- and short-range interactions, as well as encounters leading to direct collisions and mergers. The latter have long been suspected to be an important formation channel for several curious types of stars whose origins are unknown. The former drive the structural evolution of star clusters and, by leading to their eventual dissolution and the subsequent dispersal of their stars throughout the Milky Way Galaxy, have played an important role in shaping its history. Within the last few decades, theoretical work has painted a comprehensive picture for the evolution of star clusters. And yet, we are still lacking direct observational confirmation that many of the processes thought to be driving this evolution are actually occuring. The results presented in this thesis have connected several of these processes to real observations of star clusters, in many cases for the first time. This has allowed us to directly link the observed properties of several stellar populations to the physical processes responsible for their origins. We present a new method of quantifying the frequency of encounters involving single, binary and triple stars using an adaptation of the classical mean free path approximation. With this technique, we have shown that dynamical encounters involving triple stars occur commonly in star clusters, and that they are likely to be an important dynamical channel for stellar mergers to occur. This is a new result that has important implications for the origins of several peculiar types of stars (and binary stars), in particular blue stragglers. We further present several new statistical techniques that are broadly applicable to systems of dynamically-interacting particles composed of several different types of populations. These are applied to observations of star clusters in order to obtain quantitative constraints for the degree to which dynamical interactions affect the relative sizes and spatial distributions of their different stellar populations. To this end, we perform an extensive analysis of a large sample of colour-magnitude diagrams taken from the ACS Survey for Globular Clusters. The results of this analysis can be summarized as follows: (1) We have compiled a homogeneous catalogue of stellar populations, including main-sequence, main-sequence turn-off, red giant branch, horizontal branch and blue straggler stars. (2) With this catalogue, we have quantified the effects of the cluster dynamics in determining the relative sizes and spatial distributions of these stellar populations. (3) These results are particularly interesting for blue stragglers since they provide compelling evidence that they are descended from binary stars. (4) Our analysis of the main-sequence populations is consistent with a remarkably… Advisors/Committee Members: Sills, Alison, Harris, William, Harris, William, Physics and Astronomy.

Subjects/Keywords: population statistics; blue straggler; collision; dynamics; globular cluster; gravity; Stars, Interstellar Medium and the Galaxy; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Leigh, W. N. (2011). The Physics of Mergers: Theoretical and Statistical Techniques Applied to Stellar Mergers in Dense Star Clusters. (Doctoral Dissertation). McMaster University. Retrieved from http://hdl.handle.net/11375/10571

Chicago Manual of Style (16^th Edition):

Leigh, William Nathan. “The Physics of Mergers: Theoretical and Statistical Techniques Applied to Stellar Mergers in Dense Star Clusters.” 2011. Doctoral Dissertation, McMaster University. Accessed March 07, 2021. http://hdl.handle.net/11375/10571.

MLA Handbook (7^th Edition):

Leigh, William Nathan. “The Physics of Mergers: Theoretical and Statistical Techniques Applied to Stellar Mergers in Dense Star Clusters.” 2011. Web. 07 Mar 2021.

Vancouver:

Leigh WN. The Physics of Mergers: Theoretical and Statistical Techniques Applied to Stellar Mergers in Dense Star Clusters. [Internet] [Doctoral dissertation]. McMaster University; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/11375/10571.

Council of Science Editors:

Leigh WN. The Physics of Mergers: Theoretical and Statistical Techniques Applied to Stellar Mergers in Dense Star Clusters. [Doctoral Dissertation]. McMaster University; 2011. Available from: http://hdl.handle.net/11375/10571

McMaster University

23. Ward, Rachel L. Connecting the Dots: Comparing SPH Simulations and Synthetic Observations of Star-forming Clumps in Molecular Clouds.

Degree: MSc, 2011, McMaster University

URL: http://hdl.handle.net/11375/11305

►

The gravitational collapse of a giant molecular cloud produces localized dense regions, called clumps, within which low-mass star formation is believed to occur. Recent… (more)

Subjects/Keywords: Star formation; Molecular Clouds; Simulations; Synthetic Observations; Stars, Interstellar Medium and the Galaxy; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Ward, R. L. (2011). Connecting the Dots: Comparing SPH Simulations and Synthetic Observations of Star-forming Clumps in Molecular Clouds. (Masters Thesis). McMaster University. Retrieved from http://hdl.handle.net/11375/11305

Chicago Manual of Style (16^th Edition):

Ward, Rachel L. “Connecting the Dots: Comparing SPH Simulations and Synthetic Observations of Star-forming Clumps in Molecular Clouds.” 2011. Masters Thesis, McMaster University. Accessed March 07, 2021. http://hdl.handle.net/11375/11305.

MLA Handbook (7^th Edition):

Ward, Rachel L. “Connecting the Dots: Comparing SPH Simulations and Synthetic Observations of Star-forming Clumps in Molecular Clouds.” 2011. Web. 07 Mar 2021.

Vancouver:

Ward RL. Connecting the Dots: Comparing SPH Simulations and Synthetic Observations of Star-forming Clumps in Molecular Clouds. [Internet] [Masters thesis]. McMaster University; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/11375/11305.

Council of Science Editors:

Ward RL. Connecting the Dots: Comparing SPH Simulations and Synthetic Observations of Star-forming Clumps in Molecular Clouds. [Masters Thesis]. McMaster University; 2011. Available from: http://hdl.handle.net/11375/11305

McMaster University

24. McDonald, June Brittany. The Search for Supernova Light Echoes from the Core-Collapse Supernovae of AD 1054 (Crab) and AD 1181.

Degree: MSc, 2012, McMaster University

URL: http://hdl.handle.net/11375/12461

►

A deep, wide-ﬁeld survey was conducted to hunt for the light echo systems associated with SN 1054 (Crab) and SN 1181 as an initial… (more)

Subjects/Keywords: astronomy; supernova; light echoes; Stars, Interstellar Medium and the Galaxy; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

McDonald, J. B. (2012). The Search for Supernova Light Echoes from the Core-Collapse Supernovae of AD 1054 (Crab) and AD 1181. (Masters Thesis). McMaster University. Retrieved from http://hdl.handle.net/11375/12461

Chicago Manual of Style (16^th Edition):

McDonald, June Brittany. “The Search for Supernova Light Echoes from the Core-Collapse Supernovae of AD 1054 (Crab) and AD 1181.” 2012. Masters Thesis, McMaster University. Accessed March 07, 2021. http://hdl.handle.net/11375/12461.

MLA Handbook (7^th Edition):

McDonald, June Brittany. “The Search for Supernova Light Echoes from the Core-Collapse Supernovae of AD 1054 (Crab) and AD 1181.” 2012. Web. 07 Mar 2021.

Vancouver:

McDonald JB. The Search for Supernova Light Echoes from the Core-Collapse Supernovae of AD 1054 (Crab) and AD 1181. [Internet] [Masters thesis]. McMaster University; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/11375/12461.

Council of Science Editors:

McDonald JB. The Search for Supernova Light Echoes from the Core-Collapse Supernovae of AD 1054 (Crab) and AD 1181. [Masters Thesis]. McMaster University; 2012. Available from: http://hdl.handle.net/11375/12461

University of Colorado

25. Zetterlund, Erika Henning. Fuel for the Star Formation Engine: Dense Molecular Cloud Clumps in the Northern Galactic Plane.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/astr_gradetds/55

► The interstellar medium (ISM) is a confusing, muddled place. It provides the fuel for star formation, but before that can occur, the ISM must… (more)

Subjects/Keywords: interstellar medium; milky way galaxy; herschel infrared galactic; galactic plane; molecular; Astrophysics and Astronomy; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Zetterlund, E. H. (2018). Fuel for the Star Formation Engine: Dense Molecular Cloud Clumps in the Northern Galactic Plane. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/astr_gradetds/55

Chicago Manual of Style (16^th Edition):

Zetterlund, Erika Henning. “Fuel for the Star Formation Engine: Dense Molecular Cloud Clumps in the Northern Galactic Plane.” 2018. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021. https://scholar.colorado.edu/astr_gradetds/55.

MLA Handbook (7^th Edition):

Zetterlund, Erika Henning. “Fuel for the Star Formation Engine: Dense Molecular Cloud Clumps in the Northern Galactic Plane.” 2018. Web. 07 Mar 2021.

Vancouver:

Zetterlund EH. Fuel for the Star Formation Engine: Dense Molecular Cloud Clumps in the Northern Galactic Plane. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Mar 07]. Available from: https://scholar.colorado.edu/astr_gradetds/55.

Council of Science Editors:

Zetterlund EH. Fuel for the Star Formation Engine: Dense Molecular Cloud Clumps in the Northern Galactic Plane. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/astr_gradetds/55

University of Colorado

26. Martinez, Oscar, Jr. Ion-Neutral Chemistry of Importance to Astrophysical and Cosmological Environments.

Degree: PhD, Chemistry & Biochemistry, 2010, University of Colorado

URL: https://scholar.colorado.edu/chem_gradetds/25

► Scientific studies have led to a more thorough understanding of processes directing the evolution of the Universe. In addition to observational studies with telescopes,… (more)

▼ Scientific studies have led to a more thorough understanding of processes directing the evolution of the Universe. In addition to observational studies with telescopes, terrestrial laboratory studies now contribute to the knowledge encompassed by astronomy and astrophysics. The laboratory-astrophysics experiments performed for this thesis focused on topics ranging from the birth of the first stars and galaxies to chemical processes important to the interstellar medium (ISM). Models attempt to derive a better understanding of certain cosmological and astrophysical environments. Their reliability, however, depends heavily on the accuracy of data employed. Our contributions to laboratory astrophysics are based on the use of a flowing afterglow-selected ion flow tube (FA-SIFT) supported by ab initio calculations to study ion-neutral reaction kinetics. Studies for this thesis began with carbon cation, C⁺. This species, ubiquitous throughout dense-translucent and molecular-cloud regions of the ISM, is extremely reactive and is shown to lead to more complex organic species. We have measured reactions of ground-state C⁺ with abundant interstellar neutrals. Our measurements will increase the accuracy in models of the ISM. After the big bang, star and galaxy formation was not possible until the early Universe sufficiently cooled to enable protogalactic collapse. This process did not occur until a sufficient concentration of the first molecule, H₂, enabled efficient cooling. The dominant mechanism of H₂ formation during this epoch was associative detachment (AD). Because of high uncertainties in existing measurements, we have remeasured the rate constant of the AD reaction and obtained a significant improvement for cosmological models. We have also characterized the chemistry of H⁻ with prototypical chemical reactants, effectively mapping reactivity trends for hydride. The recent detection of anions in the ISM suggests that these species must play a role in the evolution of astrophysical environments. However, in contrast to their positive counterparts, relatively little is known about anion chemistry. We contribute a number of studies of anionic species, continuing the characterization of the reactions of these species and their role in astrochemistry. A number of carbanions, relevant to interstellar chemistry, were studied with the most abundant atomic species of the interstellar medium, H atom. Advisors/Committee Members: Veronica M. Bierbaum, Theodore P. Snow, Donald David.

Subjects/Keywords: Astrochemistry; Gas-Phase; Interstellar Medium; Ion-Neutral; Kinetics; Lab Astrophysics; Organic Chemistry; Physical Chemistry; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Martinez, Oscar, J. (2010). Ion-Neutral Chemistry of Importance to Astrophysical and Cosmological Environments. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/25

Chicago Manual of Style (16^th Edition):

Martinez, Oscar, Jr. “Ion-Neutral Chemistry of Importance to Astrophysical and Cosmological Environments.” 2010. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021. https://scholar.colorado.edu/chem_gradetds/25.

MLA Handbook (7^th Edition):

Martinez, Oscar, Jr. “Ion-Neutral Chemistry of Importance to Astrophysical and Cosmological Environments.” 2010. Web. 07 Mar 2021.

Vancouver:

Martinez, Oscar J. Ion-Neutral Chemistry of Importance to Astrophysical and Cosmological Environments. [Internet] [Doctoral dissertation]. University of Colorado; 2010. [cited 2021 Mar 07]. Available from: https://scholar.colorado.edu/chem_gradetds/25.

Council of Science Editors:

Martinez, Oscar J. Ion-Neutral Chemistry of Importance to Astrophysical and Cosmological Environments. [Doctoral Dissertation]. University of Colorado; 2010. Available from: https://scholar.colorado.edu/chem_gradetds/25

University of Western Ontario

27. Rajabi, Fereshteh. Dicke’s Superradiance in Astrophysics.

Degree: 2016, University of Western Ontario

URL: https://ir.lib.uwo.ca/etd/4068

► It is generally assumed that in the interstellar medium much of the emission emanating from atomic and molecular transitions within a radiating gas happen independently… (more)

Subjects/Keywords: Atomic/Molecular Processes; Interstellar Medium; Coherent Interactions; Superradiance; Maser; Physical Processes; Quantum Physics; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Rajabi, F. (2016). Dicke’s Superradiance in Astrophysics. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/4068

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Rajabi, Fereshteh. “Dicke’s Superradiance in Astrophysics.” 2016. Thesis, University of Western Ontario. Accessed March 07, 2021. https://ir.lib.uwo.ca/etd/4068.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Rajabi, Fereshteh. “Dicke’s Superradiance in Astrophysics.” 2016. Web. 07 Mar 2021.

Vancouver:

Rajabi F. Dicke’s Superradiance in Astrophysics. [Internet] [Thesis]. University of Western Ontario; 2016. [cited 2021 Mar 07]. Available from: https://ir.lib.uwo.ca/etd/4068.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Rajabi F. Dicke’s Superradiance in Astrophysics. [Thesis]. University of Western Ontario; 2016. Available from: https://ir.lib.uwo.ca/etd/4068

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Kentucky

28. Thompson, Kristen Lynn. ZEEMAN EFFECT STUDIES OF MAGNETIC FIELDS IN THE MILKY WAY.

Degree: 2012, University of Kentucky

URL: https://uknowledge.uky.edu/physastron_etds/12

► The interstellar medium (ISM) of our Galaxy, and of others, is pervaded by ultra low-density gas and dust, as well as magnetic fields. Embedded magnetic… (more)

▼ The interstellar medium (ISM) of our Galaxy, and of others, is pervaded by ultra low-density gas and dust, as well as magnetic fields. Embedded magnetic fields have been known to play an important role in the structure and dynamics of the ISM. However, the ability to accurately quantify these fields has plagued astronomers for many decades. Unfortunately, the experimental techniques for measuring the strength and direction of magnetic fields are few, and they are observationally challenging. The only direct method of measuring the magnetic field is through the Zeeman effect. The goal of this dissertation is to expand upon the current observational studies and understanding of the effects of interstellar magnetic fields across various regions of the Galaxy. Zeeman effect observations of magnetic fields in two dynamically diverse environments in the Milky Way are presented: (1) An OH and HI absorption line study of envelopes of molecular clouds distributed throughout the Galaxy, and (2) A study of OH absorption lines toward the Galactic center region in the vicinity of the supermassive black hole Sgr A*. We have executed the first systematic observational survey designed to determine the role of magnetic fields in the inter-core regions of molecular clouds. Observations of extragalactic continuum sources that lie along the line-of-sight passing through Galactic molecular clouds were studied using the Arecibo telescope. OH Zeeman effect observations were combined with estimates of column density to allow for computation of the mass-to-flux ratio, a measurement of the gravitational to magnetic energies within a cloud. We find that molecular clouds are slightly subcritical overall. However, individual measurements yield the first evidence for magnetically subcritical molecular gas. Jansky VLA observations of 18 cm OH absorption lines were used to determine the strength of the line-of-sight magnetic field in the Galactic center region. This study yields no clear detections of the magnetic field and results that differ from a similar study by Killeen, Lo, & Crutcher (1992). Our results suggest magnetic fields no more than a few microgauss in strength.

Subjects/Keywords: Galactic Center; Magnetic Fields; Molecular Clouds; Interstellar Medium; Zeeman Effect; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Thompson, K. L. (2012). ZEEMAN EFFECT STUDIES OF MAGNETIC FIELDS IN THE MILKY WAY. (Doctoral Dissertation). University of Kentucky. Retrieved from https://uknowledge.uky.edu/physastron_etds/12

Chicago Manual of Style (16^th Edition):

Thompson, Kristen Lynn. “ZEEMAN EFFECT STUDIES OF MAGNETIC FIELDS IN THE MILKY WAY.” 2012. Doctoral Dissertation, University of Kentucky. Accessed March 07, 2021. https://uknowledge.uky.edu/physastron_etds/12.

MLA Handbook (7^th Edition):

Thompson, Kristen Lynn. “ZEEMAN EFFECT STUDIES OF MAGNETIC FIELDS IN THE MILKY WAY.” 2012. Web. 07 Mar 2021.

Vancouver:

Thompson KL. ZEEMAN EFFECT STUDIES OF MAGNETIC FIELDS IN THE MILKY WAY. [Internet] [Doctoral dissertation]. University of Kentucky; 2012. [cited 2021 Mar 07]. Available from: https://uknowledge.uky.edu/physastron_etds/12.

Council of Science Editors:

Thompson KL. ZEEMAN EFFECT STUDIES OF MAGNETIC FIELDS IN THE MILKY WAY. [Doctoral Dissertation]. University of Kentucky; 2012. Available from: https://uknowledge.uky.edu/physastron_etds/12

University of Kentucky

29. Wang, Xiang. PROBING PHYSICAL CONDITIONS IN THE CRAB NEBULA WITH EMISSION LINE ANALYSIS.

Degree: 2016, University of Kentucky

URL: https://uknowledge.uky.edu/physastron_etds/36

► We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to… (more)

▼ We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict very strong emission from high ionization lines that will not be emitted by the Crab’s filaments, alleviating problems with detecting these lines in the presence of light scattered from brighter parts of the Crab. The NIR [Ne VI] λ 7.652 mm line is a particularly good case; it should be dramatically brighter than the optical lines commonly used in searches. The C IV λ1549Å doublet is predicted to be the strongest absorption line from the shell, which is in agreement with HST observations. We show that the cooling timescale for the outer shell is much longer than the age of the Crab, due to the low density. This means that the temperature of the shell will actually “remember” its initial conditions. However, the recombination time is much shorter than the age of the Crab, so the predicted level of ionization should approximate the real ionization. In any case, it is clear that IR observations present the best opportunity to detect the outer shell and so guide future models that will constrain early events in the original explosion. Infrared observations have discovered a variety of objects, including filaments in the Crab Nebula and cool-core clusters of galaxies, where the H2 1-0 S(1) line is stronger than the infrared H I lines. A variety of processes could be responsible for this emission. Although many complete shock or PDR calculations of H2 emission have been published, we know of no previous simple calculation that shows the emission spectrum and level populations of thermally excited low-density H2. We present a range of purely thermal collisional simulations, corresponding to constant gas kinetic temperature at different densities. We consider the cases where the collisions affecting H2 are predominantly with atomic or molecular hydrogen. The resulting level population (often called “excitation”) diagrams show that excitation temperatures are sometimes lower than the gas kinetic temperature when the density is too low for the level populations to go to LTE. The atomic case goes to LTE at much lower densities than the molecular case due to larger collision rates. At low densities for the v=1 and 2 vibrational manifolds level populations are quasi-thermal, which could be misinterpreted as showing the gas is in LTE at high density. At low densities for the molecular case the level population diagrams are discontinuous between v=0 and 1 vibrational manifolds and between v=2, J=0, 1 and other higher J levels within the same vibrational manifold. These jumps could be used as density diagnostics. We show how much the H2 mass would be underestimated using the H2 1-0 S(1) line strength if the density is below that…

Subjects/Keywords: supernova remnants; Crab Nebula; interstellar medium; Abell 2597; molecular hydrogen; CLOUDY; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Wang, X. (2016). PROBING PHYSICAL CONDITIONS IN THE CRAB NEBULA WITH EMISSION LINE ANALYSIS. (Doctoral Dissertation). University of Kentucky. Retrieved from https://uknowledge.uky.edu/physastron_etds/36

Chicago Manual of Style (16^th Edition):

Wang, Xiang. “PROBING PHYSICAL CONDITIONS IN THE CRAB NEBULA WITH EMISSION LINE ANALYSIS.” 2016. Doctoral Dissertation, University of Kentucky. Accessed March 07, 2021. https://uknowledge.uky.edu/physastron_etds/36.

MLA Handbook (7^th Edition):

Wang, Xiang. “PROBING PHYSICAL CONDITIONS IN THE CRAB NEBULA WITH EMISSION LINE ANALYSIS.” 2016. Web. 07 Mar 2021.

Vancouver:

Wang X. PROBING PHYSICAL CONDITIONS IN THE CRAB NEBULA WITH EMISSION LINE ANALYSIS. [Internet] [Doctoral dissertation]. University of Kentucky; 2016. [cited 2021 Mar 07]. Available from: https://uknowledge.uky.edu/physastron_etds/36.

Council of Science Editors:

Wang X. PROBING PHYSICAL CONDITIONS IN THE CRAB NEBULA WITH EMISSION LINE ANALYSIS. [Doctoral Dissertation]. University of Kentucky; 2016. Available from: https://uknowledge.uky.edu/physastron_etds/36

University of Western Ontario

30. Knight, Collin Matthew. Mid-Infrared Studies of Galactic sources: Probing the Relationship Between Polycyclic Aromatic Hydrocarbons and their Physical Environment.

Degree: 2020, University of Western Ontario

URL: https://ir.lib.uwo.ca/etd/7493

► Over the past 50 years, prominent mid-infrared (MIR) emission features from 3 – 20 μm have been observed ubiquitously in the interstellar medium (ISM) of Galactic… (more)

▼ Over the past 50 years, prominent mid-infrared (MIR) emission features from 3 – 20 μm have been observed ubiquitously in the interstellar medium (ISM) of Galactic and extragalactic sources. These emission features arise from the vibrational relaxation of polycyclic aromatic hydrocarbons (PAHs) after the absorption of a far-ultraviolet (FUV) photon. PAHs are astronomically significant in that they contain up to 15% of the cosmic carbon inventory and play an important role in the physical and chemical processes of the ISM such as, for example, the gas heating and the ionization balance. Variations in the relative strengths of the major PAH bands can be used to understand their underlying molecular properties and their interaction with the surrounding photodissociation regions (PDR) environment. We employ these variations to characterize the PAH populations in terms of properties such as degree of ionization and sizes and investigate their dependence on the physical conditions such as the FUV radiation field strength, the gas density and the gas temperature for nearby spatially resolved Galactic PDRs. We find both size and charge tend to rise with increasing radiation field strength or proximity to the illuminating source. Correlations between PAH emission features in spatially resolved sources are found to be highly dependent on the PDR morphology (i.e. edge-on versus face-on) and environmental conditions. These results are indicative of significant UV processing driving the photochemical evolution of astronomical PAH populations. We utilize observations of far-infrared (FIR) cooling lines of atoms and the FIR dust continuum emission of a nearby reflection nebula in combination with PDR models to derive maps of the physical conditions. Comparing these derived physical conditions with PAH emission characteristics at a matching spatial resolution and apertures allows us to critically test previous established relationships between PAH emission and these physical conditions. From these results, we show that these relationships also hold at a higher spatial resolution than previously obtained.

Subjects/Keywords: Polycyclic Aromatic Hydrocarbons; Photo-Dissociation Regions; Reflection Nebulae; Interstellar Medium; MIR astronomy; FIR astronomy; Stars, Interstellar Medium and the Galaxy

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APA (6^th Edition):

Knight, C. M. (2020). Mid-Infrared Studies of Galactic sources: Probing the Relationship Between Polycyclic Aromatic Hydrocarbons and their Physical Environment. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/7493

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Knight, Collin Matthew. “Mid-Infrared Studies of Galactic sources: Probing the Relationship Between Polycyclic Aromatic Hydrocarbons and their Physical Environment.” 2020. Thesis, University of Western Ontario. Accessed March 07, 2021. https://ir.lib.uwo.ca/etd/7493.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Knight, Collin Matthew. “Mid-Infrared Studies of Galactic sources: Probing the Relationship Between Polycyclic Aromatic Hydrocarbons and their Physical Environment.” 2020. Web. 07 Mar 2021.

Vancouver:

Knight CM. Mid-Infrared Studies of Galactic sources: Probing the Relationship Between Polycyclic Aromatic Hydrocarbons and their Physical Environment. [Internet] [Thesis]. University of Western Ontario; 2020. [cited 2021 Mar 07]. Available from: https://ir.lib.uwo.ca/etd/7493.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Knight CM. Mid-Infrared Studies of Galactic sources: Probing the Relationship Between Polycyclic Aromatic Hydrocarbons and their Physical Environment. [Thesis]. University of Western Ontario; 2020. Available from: https://ir.lib.uwo.ca/etd/7493

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Open Access Theses and Dissertations