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Related papers: Atomic and molecular gas properties during cloud f…

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We review recent results from numerical simulations and related models of MHD turbulence in the interstellar medium (ISM) and in molecular clouds. We discuss the implications of turbulence for the processes of cloud formation and evolution,…

Astrophysics · Physics 2007-05-23 E. Vazquez-Semadeni , E. C. Ostriker , T. Passot , C. F. Gammie , J. M. Stone

Filamentary structures are closely associated with star-forming cores, but their detailed physical connections are still not clear. We studied the dense gas in the region of OMC-3 MMS-7 in Orion A molecular cloud using the molecular lines…

Astrophysics of Galaxies · Physics 2021-07-07 Zhiyuan Ren , Lei Zhu , Hui Shi , Nannan Yue , Di Li , Qizhou Zhang , Diego Mardones , Jingwen Wu , Sihan Jiao , Shu Liu , Gan Luo , Jinjin Xie , Chao Zhang , Xuefang Xu

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

The dense cloud associated with W40, one of the nearby H II regions, has been studied in millimeter-wave molecular lines and in 1.2 mm continuum. Besides, 1280 MHz and 610 MHz interferometric observations have been done. The cloud has…

Astrophysics of Galaxies · Physics 2015-06-17 L. Pirogov , D. K. Ojha , M. Thomasson , Y. -F. Wu , I. Zinchenko

Nine HII regions of the LMC were mapped in 13CO(1--0) and three in 12CO(1--0) to study the physical properties of the interstellar medium in the Magellanic Clouds. For N113 the molecular core is found to have a peak position which differs…

Astrophysics · Physics 2007-05-23 Y. -N. Chin , C. Henkel , J. B. Whiteoak , T. J. Millar , M. R. Hunt , C. Lemme

We investigate star formation at very early evolutionary phases in five massive clouds in the inner 500 pc of the Galaxy, the Central Molecular Zone. Using interferometer observations of H$_2$O masers and ultra-compact H II regions, we find…

Population III (pop III) stars were born in halos characterised by a pristine gas composition. In such a halo, once the gas density reaches n$_{\mathrm{H}} \sim$ 1 cm$^{-3}$, molecular cooling leads to the collapse of the gas and the birth…

Astrophysics of Galaxies · Physics 2024-01-31 Romain Lenoble , Benoit Commerçon , Joakim Rosdahl

We present a new method to identify and characterize the structure of the intracluster medium (ICM) in simulated galaxy clusters. The method uses the median of gas properties, such as density and pressure, which we show to be very robust to…

High Energy Astrophysical Phenomena · Physics 2015-06-11 I. Zhuravleva , E. Churazov , A. Kravtsov , E. T. Lau , D. Nagai , R. Sunyaev

We present synthetic line observations of a simulated molecular cloud, utilising a self-consistent treatment of the dynamics and time-dependent chemical evolution. We investigate line emission from the three most common CO isotopologues…

Astrophysics of Galaxies · Physics 2024-06-12 F. D. Priestley , P. C. Clark , S. C. O. Glover , S. E. Ragan , O. Fehér , L. R. Prole , R. S. Klessen

In the currently-accepted model for star formation out of the interstellar gas in galaxies, the basic construction material is assumed to be large clouds of atomic hydrogen (HI). These clouds are thought to form higher-density complexes of…

Astrophysics · Physics 2007-05-23 Ronald J. Allen

Towards the high galactic latitude sky, the far-infrared (FIR) intensity is tightly correlated to the total hydrogen column density which is made up of atomic (HI) and molecular hydrogen (H$_{2})$. Above a certain column density threshold,…

Astrophysics of Galaxies · Physics 2015-06-18 Tobias Röhser , Jürgen Kerp , Benjamin Winkel , Francois Boulanger , Guilaine Lagache

We consider the dynamical evolution of an interstellar cloud that is initially in thermal equilibrium in the warm phase and is then subjected to a sudden increase in the pressure of its surroundings. We find that if the initial plasma beta…

Astrophysics · Physics 2009-11-13 A. J. Lim , S. A. E. G. Falle , T. W. Hartquist

An accurate estimate of the interstellar gas density distribution is crucial to understanding the interstellar medium (ISM) and Galactic cosmic rays (CRs). To comprehend the ISM and CRs in a local environment, a study of the diffuse…

High Energy Astrophysical Phenomena · Physics 2020-02-26 T. Mizuno , S. Abdollahi , Y. Fukui , K. Hayashi , T. Koyama , A. Okumura , H. Tajima , H. Yamamoto

Recent observations suggest a scenario in which filamentary structures in the ISM represent the first step towards clumps/cores and eventually star formation. The densest filaments would then fragment into prestellar cores owing to…

Astrophysics of Galaxies · Physics 2018-08-31 Gang Wu , Keping Qiu , Jarken Esimbek , Xingwu Zheng , Christian Henkel , Dalei Li , Xiaohong Han

We present three-dimensional astrochemical simulations and synthetic observations of magnetised, turbulent, self-gravitating molecular clouds. We explore various galactic interstellar medium environments, including cosmic-ray ionization…

Astrophysics of Galaxies · Physics 2021-01-20 Thomas G. Bisbas , Jonathan C. Tan , Kei E. I. Tanaka

We recently reported a population of protostellar candidates in the 20 km s$^{-1}$ cloud in the Central Molecular Zone of the Milky Way, traced by H$_2$O masers in gravitationally bound dense cores. In this paper, we report…

We report the discovery of a threshold in the HI column density of Galactic gas clouds below which the formation of the cold phase of HI is inhibited. This threshold is at $N_{HI} = 2 \times 10^{20}$ per cm$^{2}$; sightlines with lower HI…

Astrophysics of Galaxies · Physics 2013-02-20 Nissim Kanekar , Robert Braun , Nirupam Roy

We use detailed numerical simulations of the coupled chemical, thermal and dynamical evolution of the gas in a turbulent molecular cloud to study the usefulness of the [CI] 609 micron and 370 micron fine structure emission lines as tracers…

Astrophysics of Galaxies · Physics 2015-06-19 Simon C. O. Glover , Paul C. Clark , Milica Micic , Faviola Molina

We are studying the impact of HII regions on star formation in their associated molecular clouds. In this paper we present JCMT RxA molecular line observations of S175 and environs. This is the first within a sample of ten HII regions and…

Solar and Stellar Astrophysics · Physics 2015-05-13 Mohaddesseh Azimlu , Michel Fich , Carolyn McCoey