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The thermal and chemical evolution of gravitationally collapsing protostellar clouds is investigated, focusing attention on their dependence on metallicity. Calculations are carried out for a range of metallicities spanning the local…

Astrophysics · Physics 2009-10-31 Kazuyuki Omukai

The variation of an ionizing flux as a mechanism to stimulate the condensation of a diffuse gas is considered. To illustrate this effect, two situations are examined: one on the context of pregalactic conditions, and the other on the…

Astrophysics · Physics 2007-05-23 Antonio Parravano , Catherine Pech

We argue that impact velocities between dust grains with sizes less than $\sim 0.1$ $\mu m$ in molecular cloud cores are dominated by drift arising from ambipolar diffusion. This effect is due to the size dependence of the dust coupling to…

Astrophysics of Galaxies · Physics 2020-09-30 Kedron Silsbee , Alexei Ivlev , Paola Caselli , Olli Sipila , Bo Zhao

We numerically model the collapse of magnetic rotating protostellar clouds with mass of 10 $M_{sun}$. The simulations are carried out with the help of 2D MHD code Enlil. The structure of the cloud at the isothermal stage of the collapse is…

Solar and Stellar Astrophysics · Physics 2022-04-08 N. S. Kargaltseva , S. A. Khaibrakhmanov , A. E. Dudorov , S. N. Zamozdra , A. G. Zhilkin

We present models for the chemistry in gas moving towards the ionization front of an HII region. When it is far from the ionization front, the gas is highly depleted of elements more massive than helium. However, as it approaches the…

Astrophysics · Physics 2009-11-13 S. Viti , T. W. Hartquist , P. C. Myers

We investigate the spatially-resolved star formation relation using a galactic disk formed in a comprehensive high-resolution (3.8 pc) simulation. Our new implementation of stellar feedback includes ionizing radiation as well as supernova…

Astrophysics of Galaxies · Physics 2018-03-12 Ji-hoon Kim , Mark R. Krumholz , John H. Wise , Matthew J. Turk , Nathan J. Goldbaum , Tom Abel

Magnetic fields are an elemental part of the interstellar medium in galaxies. However, their impact on gas dynamics and star formation in galaxies remains controversial. We use a suite of global magnetohydrodynamical simulations of isolated…

Astrophysics of Galaxies · Physics 2019-09-25 Bastian Körtgen , Robi Banerjee , Ralph E. Pudritz , Wolfram Schmidt

Magnetic field is playing an important role at all stages of star evolution from star formation to the endpoints. The main effects are briefly reviewed. We also show that O-type stars have large convective envelopes, where convective dynamo…

Astrophysics · Physics 2009-11-13 André Maeder , Georges Meynet , Cyril Georgy , Sylvia Ekström

The density of cosmic rays inside molecular clouds determines the ionization rate in the dense cores where stars form. It is also one of the drivers of astrochemistry leading to the creation of complex molecules. Through Fermi Large Area…

High Energy Astrophysical Phenomena · Physics 2023-01-18 Rui-zhi Yang , Guang-Xing Li , Emma de Oña Wilhelmi , Yu-Dong Cui , Bing Liu , Felix Aharonian

Like their lower mass siblings, massive protostars can be expected to: a) be surrounded by circumstellar disks and b) launch magnetically-driven jets and outflows. The disk formation and global evolution is thereby controlled by advection…

Solar and Stellar Astrophysics · Physics 2023-01-18 André Oliva , Rolf Kuiper

We present results from radiation non-ideal magnetohydrodynamics (MHD) calculations that follow the collapse of rotating, magnetised, molecular cloud cores to stellar densities. These are the first such calculations to include all three…

Solar and Stellar Astrophysics · Physics 2018-02-07 James Wurster , Matthew R. Bate , Daniel J. Price

In two previous papers we formulated and solved, for a fiducial set of free parameters, the problem of the formation and evolution of a magnetically supercritical core inside a magnetically subcritical parent cloud. In this paper we present…

Astrophysics · Physics 2011-02-11 Konstantinos Tassis , Telemachos Ch. Mouschovias

The vertical temperature structure of a protoplanetary disk bears on several processes relevant to planet formation, such as gas and dust grain chemistry, ice lines and convection. The temperature profile is controlled by irradiation from…

Earth and Planetary Astrophysics · Physics 2020-05-07 William Béthune , Henrik Latter

The thermodynamical evolution of gas during the collapse of the primordial star-forming cloud depends significantly on the initial degree of rotation. However, there is no clear understanding of how the initial rotation can affect the…

Astrophysics of Galaxies · Physics 2015-12-23 Jayanta Dutta

Several sets of data show that small interstellar grains captured in interstellar magnetic fields draped over the heliosphere appear to polarize the light of nearby stars. The maximum polarization direction is offset in ecliptic longitude…

Astrophysics · Physics 2007-05-23 Priscilla C. Frisch

To constrain the nature of the very first stars, we investigate the collapse and fragmentation of primordial, metal-free gas clouds. We explore the physics of primordial star formation by means of three-dimensional simulations of the dark…

Astrophysics · Physics 2009-11-06 Volker Bromm , Paolo S. Coppi , Richard B. Larson

Massive stars provide feedback that shapes the interstellar medium of galaxies at all redshifts and their resulting stellar populations. Here we present three adaptive mesh refinement radiation hydrodynamics simulations that illustrate the…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-13 John H. Wise , Tom Abel , Matthew J. Turk , Michael L. Norman , Britton D. Smith

Magnetic fields are known to play a crucial role in the star formation process, particularly in the formation of jets and outflows from protostellar discs. The magnetic field structure in star forming regions is not always uniform and…

Solar and Stellar Astrophysics · Physics 2019-03-27 Isabella A. Gerrard , Christoph Federrath , Rajika Kuruwita

Simulations are presented of the photoionisation of three dense gas clouds threaded by magnetic fields, showing the dynamical effects of different initial magnetic field orientations and strengths. For moderate magnetic field strengths the…

Astrophysics of Galaxies · Physics 2013-01-08 Jonathan Mackey , Andrew J. Lim

Massive protostars launch accretion-powered, magnetically-collimated outflows, which play crucial roles in the dynamics and diagnostics of the star formation process. Here we calculate the shock heating and resulting free-free radio…

Astrophysics of Galaxies · Physics 2023-09-08 Emiko C. Gardiner , Jonathan C. Tan , Jan E. Staff , Jon P. Ramsey , Yichen Zhang , Kei E. Tanaka