Mass Assembly in Star Formation Via Interstellar Filaments


Book Description

Understanding how diffuse molecular clouds at large scales (~10 pc) assemble mass into dense, star-forming cores at small scales (~ 0.1 pc) is crucial to building a holistic theory of star formation. While recent observations suggest that filaments play an important role in the mass assembly of dense cores, detailed gas kinematics studies are still lacking. My dissertation presents three innovative techniques that enable us to study star-forming filaments' complex gas kinematics in unprecedented detail: multi-component spectral fit, multi-dimensional filament identification, and membership assignment of velocity-coherent structures. Through these techniques, I analyzed star-forming filaments in the Perseus Molecular Cloud and unveiled unexpectedly complex velocity structures at scales where filaments are well resolved, to as low as the 0.01 pc scale. Moreover, the correlations I discovered between the various filament properties further suggest a scenario in which thermally supercritical filaments grow continuously via accretion from their surroundings while simultaneously forming cores through fragmentation along their lengths.




Star Formation, Galaxies and the Interstellar Medium


Book Description

The enormously powerful phenomena of starbursts are examined in this book. These spectacular star-forming events are seen on large scales in some galaxies, often triggered by galactic interactions. An intriguing implication of starburst research is that active galactic nuclei (AGN) may not be powered by accreting black holes. Instead theories are presented where compact powerhouses of dust-enshrouded star formation lie at the core of AGN, with supernovae exploding roughly once per year within massive nuclear concentrations of gas. This book collects articles from a timely international conference in Elba, Italy, in 1992; these comprise a thorough review of the most important developments in galactic-scale star formation since the starburst revolution of the late 1980s. This text will introduce graduate students to this exciting area and keep experts apace with rapid developments in it.




Stellar Formation


Book Description

Stellar Formation focuses on the properties, distributions, characteristics, and formation of stars and galaxies. The manuscript first offers information on locations of star formation, as well as the distribution of interstellar gas, clouds, and globules; spatial relationships between young stars and interstellar matter; and distribution of young stars. The book also tackles frequency distribution of stellar masses and aggregates of stars. The text ponders on the frequency distribution of cloud masses, rate and environment of star formation, and cloud structure in the interstellar gas. The publication also examines the fragmentation of clouds into protostars and the frequency distribution of protostar masses, rate of formation of stars, and evolution of galaxies. Discussions focus on random fragmentation, gravitational turbulence, and fragmentation induced by molecule formation. The manuscript is a vital reference for scientists and readers interested in stellar formation.




Star Formation in Galaxy Evolution: Connecting Numerical Models to Reality


Book Description

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.







The Earliest Stages of Massive Clustered Star Formation: Fragmentation of Infrared Dark Clouds


Book Description

This thesis presents an in-depth, high-resolution observational study on the very beginning of the formation process: the fragmentation of dense molecular clouds known as infrared dark clouds (IRDCs). Using the Submillimeter Array (SMA) and Very Large Array (VLA) radio interferometers, the author has discovered a common picture of hierarchical fragmentation that challenges some of the leading theoretical models and suggests a new, observation-driven understanding of how massive star formation in clustered environments may begin: it is initiated by the hierarchical fragmentation of a dense filament from 10 pc down to 0.01 pc, and the stellar mass buildup is simultaneously fed by hierarchical accretion at similar scales. The new scenario points out the importance of turbulence and filamentary structure, which are now receiving increasing attention and further tests from both observers and theorists.













Star Formation


Book Description

'Krumholz has a strong writing style, didactic to be sure, but also fairly conversational within the limits of the material. While hardly casual reading, this text would be a good resource for a stellar astrophysicist, or any individual seeking to become one.'CHOICEThis book provides a modern introduction to the study of star formation, at a level suitable for graduate students or advanced undergraduates in astrophysics. The first third of the book provides a review of the observational phenomenology and then the basic physical processes that are important for star formation. The remainder then discusses the major observational results and theoretical models for star formation on scales from galactic down to planetary. The book includes recommendations for complementary reading from the research literature, as well as five problem sets with solutions.