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The formation of protostars and their disks has been understood as the result of the gravitational collapse phase of an accumulation of dense gas that determines the mass reservoir of the star-disk system. Against this background, the…

Solar and Stellar Astrophysics · Physics 2024-06-18 M. Kuffmeier

We present the latest development of the disk gravitational instability and fragmentation model, originally introduced by us to explain episodic accretion bursts in the early stages of star formation. Using our numerical hydrodynamics model…

Solar and Stellar Astrophysics · Physics 2015-06-03 Eduard I. Vorobyov , Shantanu Basu

Young stars exhibit variability due to changes in the gas accretion rate onto them, an effect that should be quite significant in the early stages of their formation. As protostars are embedded within their natal cloud, this variability may…

The evolution of protostellar outflows is investigated under different mass accretion rates in the range $\sim10^{-5}-10^{-2} {\rm M}_\odot$ yr$^{-1}$ with three-dimensional magnetohydrodynamic simulations. A powerful outflow always appears…

Astrophysics of Galaxies · Physics 2020-10-21 Masahiro N. Machida , Takashi Hosokawa

The complexity of physico-chemical models of star formation is increasing, with models that take into account new processes and more realistic setups. These models allow astrochemists to compute the evolution of chemical species throughout…

Astrophysics of Galaxies · Physics 2019-07-17 Thomas H. G. Vidal , Pierre Gratier , Neil Vaytet , Audrey Coutens , Valentine Wakelam

We investigate the thermal and dynamical evolution of primordial gas clouds in the universe after decoupling. Comparing the time-scale of dynamical evolution with that of fragmentation, we can estimate the typical fragmentation scale. We…

Astrophysics · Physics 2009-10-31 Ryoichi Nishi , Hajime Susa , Hideya Uehara , Masako Yamada , Kazuyuki Omukai

We develop a semi-analytic formalism for the determination of the evolution of the stellar mass accretion rate for specified density and velocity profiles that emerge from the runaway collapse of a prestellar cloud core. In the early phase,…

Solar and Stellar Astrophysics · Physics 2022-06-29 Indrani Das , Shantanu Basu

Protostars likely accrete material at a highly time variable rate, however, measurements of accretion variability from the youngest protostars are rare, as they are still deeply embedded within their envelopes. Sub-mm/mm observations can…

The bright maser emission produced by several molecular species at centimeter to long millimeter wavelengths provides an essential tool for understanding the process of massive star formation. Unimpeded by the high dust optical depths that…

We formulate the problem of the formation and subsequent evolution of fragments (or cores) in magnetically-supported, self-gravitating molecular clouds in two spatial dimensions. The six-fluid (neutrals, electrons, molecular and atomic…

Astrophysics · Physics 2011-02-11 Matthew W. Kunz , Telemachos Ch. Mouschovias

By performing three-dimensional radiation hydrodynamics simulations, we study the formation of young massive star clusters (YMCs, $M_{*}>10^4~M_{\odot}$) in clouds with the surface density ranging from $\Sigma_{\rm cl} = 80$ to…

Astrophysics of Galaxies · Physics 2021-08-18 Hajime Fukushima , Hidenobu Yajima

Molecular clouds interacting with supernova remnants may be subject to a greatly enhanced irradiation by cosmic rays produced at the shocked interface between the ejecta and the molecular gas. Over the past decade, broad-band observations…

Astrophysics · Physics 2009-11-11 M. Fatuzzo , F. C. Adams , F. Melia

Using hydrodynamic simulations we investigate the rotational properties and angular momentum evolution of prestellar and protostellar cores formed from gravoturbulent fragmentation of interstellar gas clouds. We find the specific angular…

Astrophysics · Physics 2009-11-10 A. -K. Jappsen , R. S. Klessen

Two scenarios have been proposed for evolution of star forming cores: gravitational fragmentation of larger structures and coalescence of smaller entities which are formed from some instabilities. Here, we turn our attention to the latter…

Astrophysics of Galaxies · Physics 2015-05-18 M. Nejad-Asghar

We present a model for the radiative output of star clusters in the process of star formation suitable for use in hydrodynamical simulations of radiative feedback. Gas in a clump, defined as a region whose density exceeds 10^4 cm^-3, is…

Astrophysics of Galaxies · Physics 2015-06-18 Corey S. Howard , Ralph E. Pudritz , William E. Harris

One of the key problems in star formation research is to determine the role of magnetic fields. Starting from the atomic inter-cloud medium (ICM) which has density nH ~ 1 per cubic cm, gas must accumulate from a volume several hundred pc…

Astrophysics of Galaxies · Physics 2015-05-13 Hua-bai Li , C. Darren Dowell , Alyssa Goodman , Roger Hildebrand , Giles Novak

We examined the gravitational contraction of isothermal molecular cloud cores with slow rotation by means of two-dimensional numerical simulations. Applying a sink-cell method, we followed the evolution of the cloud cores up to the stages…

Astrophysics · Physics 2009-10-31 Fumitaka Nakamura

It has been known for more than 30 years that star formation in giant molecular clouds (GMCs) is slow, in the sense that only ~1% of the gas forms stars every free-fall time. This result is entirely independent of any particular model of…

Astrophysics · Physics 2008-11-26 Mark R. Krumholz , Jonathan C. Tan

In this study, the main goal is to understand the molecular cloud core collapse through the stages of first and second hydrostatic core formation. We investigate the properties of Larson's first and second cores following the evolution of…

Solar and Stellar Astrophysics · Physics 2018-10-24 Asmita Bhandare , Rolf Kuiper , Thomas Henning , Christian Fendt , Gabriel-Dominique Marleau , Anders Kölligan

Disc fragmentation provides an important mechanism for producing low mass stars in prestellar cores. Here, we describe Smoothed Particle Hydrodynamics simulations which show how populations of prestellar cores evolve into stars. We find the…

Solar and Stellar Astrophysics · Physics 2016-02-03 O. Lomax , A. P. Whitworth , D. A. Hubber
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