Star Formation Efficiency in the Turbulent, Interstellar Medium (ISM)

Star Formation Efficiency in the Turbulent, Interstellar Medium (ISM)
Title Star Formation Efficiency in the Turbulent, Interstellar Medium (ISM) PDF eBook
Author Manuel Oliver Stubbe
Publisher
Pages
Release 2020
Genre
ISBN

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Star Formation in Galaxy Evolution: Connecting Numerical Models to Reality

Star Formation in Galaxy Evolution: Connecting Numerical Models to Reality
Title Star Formation in Galaxy Evolution: Connecting Numerical Models to Reality PDF eBook
Author Nickolay Y. Gnedin
Publisher Springer
Pages 375
Release 2015-09-09
Genre Science
ISBN 3662478900

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This book contains the elaborated and updated versions of the 24 lectures given at the 43rd Saas-Fee Advanced Course. Written by four eminent scientists in the field, the book reviews the physical processes related to star formation, starting from cosmological down to galactic scales. It presents a detailed description of the interstellar medium and its link with the star formation. And it describes the main numerical computational techniques designed to solve the equations governing self-gravitating fluids used for modelling of galactic and extra-galactic systems. This book provides a unique framework which is needed to develop and improve the simulation techniques designed for understanding the formation and evolution of galaxies. Presented in an accessible manner it contains the present day state of knowledge of the field. It serves as an entry point and key reference to students and researchers in astronomy, cosmology, and physics.

Interstellar Turbulence

Interstellar Turbulence
Title Interstellar Turbulence PDF eBook
Author José Franco
Publisher Cambridge University Press
Pages 304
Release 1999-05-28
Genre Science
ISBN 9780521651318

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This timely volume presents a series of review articles covering every aspect of interstellar turbulence--from accretion disks, molecular clouds, atomic and ionized media, through to spiral galaxies - based on a major international conference held in Mexico City.With advances in observational techniques and the development of more efficient computer codes and faster computers, research in this area has made spectacular progress in recent years. This book provides a comprehensive overview of the most important developments in observing and modelling turbulent flows in the cosmos. It provides graduate student and researchers with a state-of-the-art summary of observational, theoretical and computational research in interstellar turbulence.

Drivers of Turbulence in the Neutral Interstellar Medium of Dwarf Galaxies

Drivers of Turbulence in the Neutral Interstellar Medium of Dwarf Galaxies
Title Drivers of Turbulence in the Neutral Interstellar Medium of Dwarf Galaxies PDF eBook
Author Adrienne M. Stilp
Publisher
Pages 414
Release 2013
Genre Atomic hydrogen
ISBN

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The cause of HI velocity dispersions in the interstellar medium (ISM) of galaxies is often attributed to star formation, but recent evidence has shown these two quantities are not connected in regions of low star formation. This lack of connection is most apparent in dwarf galaxies and the outer disks of spiral galaxies. However, unique data sets have recently been collected that can help address this discrepancy. The ACS Nearby Survey Treasury Project (ANGST) has measured time-resolved star formation histories (SFHs) in ~70 nearby galaxies. The followup Very Large Array-ANGST survey (VLA-ANGST) provides complementary HI observations of a subset of ANGST galaxies. In this thesis, I explore the connection between star formation and HI kinematics in a number of nearby dwarf galaxies. I first present the Very Large Array-ACS Nearby Galaxy Survey Treasury Project (ANGST). VLA-ANGST was designed to provide high spatial and velocity resolution observations of the HI component of the interstellar medium (ISM) in ANGST galaxies. I describe the data calibration and imaging procedures, and then present the publicly-available data products. The observations from this survey and from The HI Nearby Galaxy Survey (THINGS) comprise the majority of data in my thesis. Using VLA-ANGST and THINGS data, I present a method to measure the average HI kinematics in a number of nearby dwarf galaxies by co-adding individual line-of-sight profiles. These "superprofiles" are composed of a central narrow peak (6-10 km/s) with higher velocity wings to either side. When scaled to the same half-width half-maximum, the shapes of the superprofiles are very similar. I interpret the central peak as representative of the average turbulent motion; the wings are then due to HI moving faster than expected compared to the average kinematics. I then compare the superprofile parameters to physical properties such as mass surface density and star formation intensity. The average velocity dispersion correlate most strongly with HI surface density, and do not show correlations with star formation intensity unless higher mass galaxies were included. The properties of the wings are more connected with star formation. By applying energy arguments, I determine that star formation can provide enough energy to drive the HI kinematics over 10 Myr timescales, while a gravitational instability cannot. I then extend this analysis to spatially-resolved scales in these galaxies, and generated superprofiles in regions determined by radius or by star formation intensity. These superprofiles provide a more direct comparison between HI kinematics and local ISM properties compared to the analysis on global scales. The spatially-resolved superprofiles indicate that star formation does not uniquely determine the HI velocity dispersion, but it does appear to provide a lower floor below which velocity dispersions cannot fall. I also find that the coupling efficiency between star formation and HI kinematics decreases with increasing star formation surface density, which may indicate that star formation energy couples more consistently to other phases of the ISM. I finally explore the timescale over which HI responds to star formation using a combination of VLA-ANGST, THINGS, and ANGST data. Using time-resolved SFHs from ANGST, I measure the average star formation rate as a function of time and compared it to present-day HI kinematics. I find that the HI kinematics are most strongly correlated with star formation that occurred 30-40 Myr ago, which supports the idea that supernova explosions are one driver of HI kinematics even in low star formation systems.

Triggered Star Formation in a Turbulent Interstellar Medium (IAU S237)

Triggered Star Formation in a Turbulent Interstellar Medium (IAU S237)
Title Triggered Star Formation in a Turbulent Interstellar Medium (IAU S237) PDF eBook
Author International Astronomical Union. Symposium
Publisher Cambridge University Press
Pages 544
Release 2007-05-28
Genre Science
ISBN 9780521863469

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New stars form in the dense turbulent gas clouds of galaxies, and the formation of these clouds is the subject of the IAU S237. This book is the most up-to-date review of all aspects of cloud and star formation, and one of the few compendiums available on ISM turbulence.

The Interstellar Medium, Expanding Nebulae and Triggered Star Formation

The Interstellar Medium, Expanding Nebulae and Triggered Star Formation
Title The Interstellar Medium, Expanding Nebulae and Triggered Star Formation PDF eBook
Author Thomas G. Bisbas
Publisher Springer
Pages 82
Release 2015-11-24
Genre Science
ISBN 3319261428

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This brief brings together the theoretical aspects of star formation and ionized regions with the most up-to-date simulations and observations. Beginning with the basic theory of star formation, the physics of expanding HII regions is reviewed in detail and a discussion on how a massive star can give birth to tens or hundreds of other stars follows. The theoretical description of star formation is shown in simplified and state-of-the-art numerical simulations, describing in a more clear way how feedback from massive stars can trigger star and planet formation. This is also combined with spectacular images of nebulae taken by talented amateur astronomers. The latter is very likely to stimulate the reader to observe the structure of nebulae from a different point of view, and better understand the associated star formation therein.

The Interstellar Medium in External Galaxies

The Interstellar Medium in External Galaxies
Title The Interstellar Medium in External Galaxies PDF eBook
Author David J. Hollenbach
Publisher
Pages 452
Release 1990
Genre Astrophysics
ISBN

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