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相关论文: Physical properties of a very diffuse HI structure…

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We carried out synthetic observations of interstellar atomic hydrogen at 21cm wavelength by utilizing the magneto-hydrodynamical numerical simulations of the inhomogeneous turbulent interstellar medium (ISM) Inoue and Inutsuka (2012). The…

The transition from the diffuse warm neutral medium (WNM) to the dense cold neutral medium (CNM) is what set the initial conditions to the formation of molecular clouds. The properties of the turbulent cascade in the WNM, essential to…

星系天体物理 · 物理学 2021-03-03 Antoine Marchal , Marc-Antoine Miville-Deschênes

This paper is a numerical study of the condensation of the warm neutral medium (WNM) into cold neutral medium (CNM) structures under the effect of turbulence and thermal instability. Using low resolution simulations we explored the impact…

星系天体物理 · 物理学 2014-07-09 E. Saury , M. -A. Miville-Deschênes , P. Hennebelle , E. Audit , W. Schmidt

Observations of intergalactic neutral hydrogen can provide a wealth of information about structure and galaxy formation, potentially tracing accretion and feedback processes on Mpc scales. Below a column density of NHI ~ 10^19 cm-2, the…

宇宙学与河外天体物理 · 物理学 2015-05-13 Attila Popping , Romeel Dave , Robert Braun , Benjamin D. Oppenheimer

We report Arecibo 21 cm absorption-emission observations to characterise the physical properties of neutral hydrogen (HI) in the proximity of five giant molecular clouds (GMCs): Taurus, California, Rosette, Mon OB1, and NGC 2264. Strong HI…

We have obtained deep HI observations in the direction of 22 continuum sources without previously detected cold neutral medium (CNM). 18 CNM clouds were detected with the typical HI column density of $3\times10^{18}$ cm$^{-2}$. Our…

天体物理学 · 物理学 2007-05-23 Snezana Stanimirovic , Carl Heiles , Nissim Kanekar

We use the Gaussian-fit results of Paper I to investigate the properties of interstellar HI in the Solar neighborhood. The Warm and Cold Neutral Media (WNM and CNM) are physically distinct components. The CNM spin temperature histogram…

天体物理学 · 物理学 2010-04-06 Carl Heiles , T. H. Troland

We discuss physical conditions in Galactic neutral hydrogen based on deep, high velocity resolution interferometric HI 21 cm absorption spectroscopy towards 33 compact extra-galactic radio sources. The HI 21 cm optical depth spectra have…

星系天体物理 · 物理学 2014-07-30 Nirupam Roy , Nissim Kanekar , Jayaram N. Chengalur

Context. A large fraction of the interstellar medium can be characterized as a multiphase medium. The neutral hydrogen gas is bistable with a cold and warm neutral medium (CNM and WNM respectively) but there is evidence for an additional…

星系天体物理 · 物理学 2018-11-07 P. M. W. Kalberla , U. Haud

We present 21-cm Spectral Line Observations of Neutral Gas with the VLA (21-SPONGE), a Karl G. Jansky Very Large Array (VLA) large project (~600 hours) for measuring the physical properties of Galactic neutral hydrogen (HI). 21-SPONGE is…

Context. The HI distribution at high Galactic latitudes is found to be filamentary and closely related to the far infrared (FIR) in caustics with coherent velocity structures. These structures trace the orientation of the magnetic field…

星系天体物理 · 物理学 2025-02-04 P. M. W. Kalberla

{We study in some details the statistical properties of the turbulent 2-phase interstellar atomic gas.{We present high resolution bidimensional numerical simulations of the interstellar atomic hydrogen which describe it over 3 to 4 orders…

天体物理学 · 物理学 2015-06-24 P. Hennebelle , E. Audit

We investigate data from the Galactic Effelsberg--Bonn HI Survey (EBHIS), supplemented with data from the third release of the Galactic All Sky Survey (GASS III) observed at Parkes. We explore the all sky distribution of the local Galactic…

星系天体物理 · 物理学 2016-04-27 P. M. W. Kalberla , J. Kerp , U. Haud , B. Winkel , N. Ben Bekhti , L. Floeer , D. Lenz

The warm neutral medium (WNM) was thought to be subsonically/transonically turbulent, and it lacks a network of intertwined filaments that are commonly seen in both molecular clouds and cold neutral medium (CNM). Here, we report HI~21 cm…

Neutral hydrogen 21 cm transition is a useful tracer of the neutral interstellar medium. However, inferring physical condition from the observed 21 cm absorption and/or emission spectra is often not straightforward. One complication in…

星系天体物理 · 物理学 2021-01-13 Atanu Koley , Nirupam Roy

The 21 cm hyperfine transition of the atomic hydrogen (HI) in ground state is a powerful probe of the neutral gas content of the universe. This radio frequency transition has been used routinely for decades to observe, both in emission and…

星系天体物理 · 物理学 2019-11-26 Preetha Saha , Nirupam Roy , Mukul Bhattacharya

A set of diffuse interstellar clouds in the inner Galaxy within a few hundred pc of the Galactic plane has been observed at an angular resolution of ~1 arcmin combining data from the NRAO Green Bank Telescope and the Very Large Array. At…

星系天体物理 · 物理学 2015-06-15 Yurii Pidopryhora , Felix J. Lockman , John M. Dickey , Michael P. Rupen

{It is necessary to understand the dynamics of the atomic gas to use complex modeling and to carry out detailed comparisons between theoretical models and observations.}{In a companion paper, we present high resolution bidimensional…

天体物理学 · 物理学 2007-05-23 P. Hennebelle , E. Audit , M. -A Miville-Deschenes

Atomic Hydrogen-21 cm transition (HI) is an excellent tracer to study and understand the properties of the atomic gas in the Galaxy. Using the Westerbork Synthesis Radio Telescope (WSRT), we observed 12 quasar sightlines to detect galactic…

星系天体物理 · 物理学 2024-03-19 Narendra Nath Patra , Nirupam Roy

We present deep HI observations of the compact high-velocity cloud HVC125+41-207 using the 100-m Effelsberg telescope. Our goal was in particular to study the warm neutral medium (WNM) in detail. The Effelsberg data reveal a two phase…

天体物理学 · 物理学 2009-11-06 C. Bruens , J. Kerp , A. Pagels
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