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We study star cluster formation in various environments with different metallicities and column densities by performing a suite of three-dimensional radiation hydrodynamics simulations. We find that the photoionization feedback from massive…

Astrophysics of Galaxies · Physics 2020-08-25 Hajime Fukushima , Hidenobu Yajima , Kazuyuki Sugimura , Takashi Hosokawa , Kazuyuki Omukai , Tomoaki Matsumoto

Polarization carries information about the magnetic fields in interstellar clouds. The observations of polarized dust emission are used to study the role of magnetic fields in the evolution of molecular clouds and the initial phases of…

Astrophysics of Galaxies · Physics 2015-05-13 V. -M. Pelkonen , M. Juvela , P. Padoan

Magnetic fields of molecular clouds in the Central Molecular Zone (CMZ) have been relatively underobserved at sub-parsec resolution. Here we report JCMT/POL2 observations of polarized dust emission in the CMZ, which reveal magnetic field…

Requirements for magnetic coupling and accretion in the active layer of a protostellar disk are re-examined, and some implications for thermal emission from the layer are discussed. The ionization and electrical conductivity are calculated…

Solar and Stellar Astrophysics · Physics 2009-08-05 Xue-Ning Bai , Jeremy Goodman

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

Massive stars disproportionately influence their surroundings. How they form has only started to become clear recently through radiation gas dynamical simulations. However, until now, no simulation has simultaneously included both magnetic…

Solar and Stellar Astrophysics · Physics 2015-03-17 Thomas Peters , Robi Banerjee , Ralf S. Klessen , Mordecai-Mark Mac Low

We study the effect that non-equilibrium chemistry in dynamical models of collapsing molecular cloud cores has on measurements of the magnetic field in these cores, the degree of ionization, and the mean molecular weight of ions. We find…

Astrophysics of Galaxies · Physics 2015-06-03 Konstantinos Tassis , Karen Willacy , Harold W. Yorke , Neal Turner

Star formation occurs in dark molecular regions where the number density of hydrogen nuclei, nH, exceeds 10^4 cc and the fractional ionization is 10^-7 or less. Dust grains with sizes ranging up to tenths of microns and perhaps down to tens…

Plasma Physics · Physics 2015-05-14 S. Van Loo , S. A. E. G. Falle , T. W. Hartquist , O. Havnes , G. E. Morfill

Star-forming gas clouds are strongly magnetized, and their ionization fractions are high enough to place them close to the regime of ideal magnetohydrodyamics on all but the smallest size scales. In this review we discuss the effects of…

Astrophysics of Galaxies · Physics 2019-02-08 Mark R. Krumholz , Christoph Federrath

We explore the effects of magnetic energy dissipation on the formation of the first stars. For this purpose, we follow the evolution of primordial chemistry in the presence of magnetic fields in the post-recombination universe until the…

Cosmology and Nongalactic Astrophysics · Physics 2009-09-28 Dominik R. G. Schleicher , Daniele Galli , Simon C. O. Glover , Robi Banerjee , Francesco Palla , Raffaella Schneider , Ralf S. Klessen

We investigate the detailed processes working in the drift of magnetic fields in molecular clouds. To the frictional force, whereby the magnetic force is transmitted to neutral molecules, ions contribute more than half only at cloud…

Astrophysics · Physics 2009-11-07 Takenori Nakano , Ryoichi Nishi , Toyoharu Umebayashi

In a low-metallicity gas, rapid cooling by dust thermal emission is considered to induce cloud fragmentation and play a vital role in the formation of low-mass stars (<~ 1 M_sun) in metal-poor environments. We investigate how the growth of…

Astrophysics of Galaxies · Physics 2013-02-13 Gen Chiaki , Takaya Nozawa , Naoki Yoshida

Wind models of very massive stars with metallicities in a range from 1E-4 to 1.0 solar are calculated using a new treatment of radiation driven winds with depth dependent radiative force multipliers and a comprehensive list of more than two…

Astrophysics · Physics 2011-06-21 Rolf P. Kudritzki

Observations of infrared fine-structure lines provide direct information on the metallicity and ionization structure of HII regions and indirectly on the hardness of the radiation field ionizing these nebulae. We have analyzed a sample of…

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

In this chapter we review recent advances in understanding the roles that magnetic fields play throughout the star formation process, gained through observations and simulations of molecular clouds, the dense, star-forming phase of the…

Astrophysics of Galaxies · Physics 2022-03-22 Kate Pattle , Laura Fissel , Mehrnoosh Tahani , Tie Liu , Evangelia Ntormousi

The collapse of dense cores with different metallicities is studied by hydrodynamical calculations coupled with detailed chemical and radiative processes. For this purpose, we construct a simple chemical network with non-equilibrium…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Kazuyuki Omukai , Takashi Hosokawa , Naoki Yoshida

We investigate the process of self-regulated star formation via photodissociation of hydrogen molecules in low metallicity clouds. We evaluate the influence region's scale of a massive star in low metallicity gas clouds whose temperatures…

Astrophysics · Physics 2009-10-31 Ryoichi Nishi , Motomichi Tashiro

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

The model is constructed of the propagation of gamma-ray burst radiation through a dense molecular cloud. The main processes of the interaction of the radiation with the interstellar gas are taken into account in the simulations: the…

High Energy Astrophysical Phenomena · Physics 2024-05-20 Aleksandr Nesterenok