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In the absence of magnetic fields and cosmic rays, radiative cooling laws with a range of dependences on temperature affect the stability of interstellar gas. For about four and a half decades, astrophysicists have recognised the importance…

Astrophysics of Galaxies · Physics 2011-08-08 T. W. Hartquist , A. Y. Wagner , S. A. E. G. Falle , J. M. Pittard , S. Van Loo

Cosmic rays are appealing as a source of ionization in starburst galaxies because of the great columns they can penetrate, but in the densest regions of starbursts, they may be stopped by pion production and ionization energy losses. I…

High Energy Astrophysical Phenomena · Physics 2012-04-13 Brian C. Lacki

Observations of protoplanetary disks suggest that the gas and dust follow significantly different radial distributions. This finding can be theoretically explained by a combination of radial drift and gas drag of intermediate-sized dust…

Solar and Stellar Astrophysics · Physics 2016-01-13 L. Ilsedore Cleeves

The early evolution of protostellar, star-forming discs, including their density structure, turbulence, magnetic dynamics, and accretion variability, remains poorly understood. We present high-resolution magnetohydrodynamic simulations,…

Solar and Stellar Astrophysics · Physics 2025-08-28 Trey Qingyun Yang , Christoph Federrath

We present collapse simulations of strongly magnetised, 100 M_sun, turbulent cloud cores. Around the protostars formed during the collapse Keplerian discs with typical sizes of up to 100 AU build up in contrast to previous simulations…

Astrophysics of Galaxies · Physics 2015-06-11 D. Seifried , R. Banerjee , R. E. Pudritz , R. S. Klessen

We study dissipation process of magnetic fields in the metallicity range $0-1 Z_{\odot}$ for contracting prestellar cloud cores. By solving non-equilibrium chemistry for important charged species including charged grains, we evaluate the…

Solar and Stellar Astrophysics · Physics 2015-06-23 Hajime Susa , Kentaro Doi , Kazuyuki Omukai

The presence of small amounts of atomic hydrogen, detected as absorption dips in the 21 cm line spectrum, is a well-known characteristic of dark clouds. The abundance of hydrogen atoms measured in the densest regions of molecular clouds can…

Astrophysics of Galaxies · Physics 2018-11-21 Marco Padovani , Daniele Galli , Alexei V. Ivlev , Paola Caselli , Andrea Ferrara

The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology via reconnection in highly conducting media. Recent progress in understanding…

Astrophysics of Galaxies · Physics 2012-12-17 R. Santos-Lima , A. Lazarian , E. M. de Gouveia Dal Pino , J. Cho

We investigate the formation of circumstellar disks and outflows subsequent to the collapse of molecular cloud cores with the magnetic field and turbulence. Numerical simulations are performed by using an adaptive mesh refinement to follow…

Solar and Stellar Astrophysics · Physics 2017-04-26 Tomoaki Matsumoto , Masahiro N. Machida , Shu-ichiro Inutsuka

Cosmic-ray-induced sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of…

Astrophysics of Galaxies · Physics 2021-04-07 E. Dartois , M. Chabot , T. Id Barkach , H. Rothard , P. Boduch , B. Augé , A. N. Agnihotri

The theory of Galactic Winds, driven by the cosmic-ray pressure gradient, is reviewed both on the magnetohydrodynamic and on the kinetic level. In this picture the magnetic field of the Galaxy above the dense gas disk is assumed to have a…

High Energy Astrophysical Phenomena · Physics 2014-11-06 Heinrich J. Völk

Motivated by recent observational and numerical studies suggesting that collapsing protostellar cores may be replenished from the local environment, we explore the evolution of protostellar cores submerged in the external counter-rotating…

Solar and Stellar Astrophysics · Physics 2016-03-23 Eduard I. Vorobyov , Zsolt Regaly , Manuel Guedel , D. N. C. Lin

Some part of the relic Dark Matter is distributed in small-scale clumps which survived structure formation in inflation cosmological scenario. The annihilation of DM inside these clumps is a strong source of stable charged particles which…

Astrophysics · Physics 2007-10-01 W. de Boer , V. Zhukov

Star formation is thought to be triggered by gravitational collapse of the dense cores of molecular clouds. Angular momentum conservation during the collapse results in the progressive increase of the centrifugal force, which eventually…

Earth and Planetary Astrophysics · Physics 2015-05-28 Raquel Salmeron

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

Planet formation in protoplanetary discs requires dust grains to coagulate from the sub-micron sizes that are found in the interstellar medium into much larger objects. For the first time, we study the growth of dust grains during the…

Astrophysics of Galaxies · Physics 2022-06-01 Matthew R. Bate

We explore the impact of diffusive cosmic rays (CRs) on the evolution of the interstellar medium (ISM) under varying assumptions of supernova explosion environment. In practice, we systematically vary the relative fractions of supernovae…

Astrophysics of Galaxies · Physics 2022-12-28 Christine M. Simpson , Rüdiger Pakmor , Christoph Pfrommer , Simon C. O. Glover , Rowan Smith

While cosmic rays $(E\gtrsim 1\,\mathrm{GeV})$ are well coupled to a galaxy's interstellar medium (ISM) at scales of $L>100\,\mathrm{pc}$, adjusting stratification and driving outflows, their impact on small scales is less clear. Based on…

High Energy Astrophysical Phenomena · Physics 2024-10-03 Roark Habegger , Ka Wai Ho , Ka Ho Yuen , Ellen G. Zweibel

In the context of star and planet formation, understanding the formation of disks is of fundamental importance. Previous studies found that the magnetic field has a very strong impact on the collapse of a prestellar cloud, particularly in…

Astrophysics of Galaxies · Physics 2015-05-14 P. Hennebelle , A. Ciardi

Stars and more particularly massive stars, have a drastic impact on galaxy evolution. Yet the conditions in which they form and collapse are still not fully understood. In particular, the influence of the magnetic field on the collapse of…

Astrophysics of Galaxies · Physics 2015-05-27 P. Hennebelle , B. Commercon , M. Joos , R. S. Klessen , M. Krumholz , J. C. Tan , R. Teyssier