Modeling the Neutral Hydrogen Interstellar Medium: A Better Kinematic Distance Tool

2006 ◽  
Vol 644 (1) ◽  
pp. 214-228 ◽  
Author(s):  
T. Foster ◽  
J. MacWilliams
Keyword(s):  
Interstellar Medium ◽  
Neutral Hydrogen

The HRS GTO program to study the neutral hydrogen column density and D/H ratio in the local interstellar medium

1986 ◽  
Vol 6 (2) ◽  
pp. 91-94
Author(s):  
J.L. Linsky, ◽  
W.B. Landsman ◽  
B.D. Savage ◽  
S.R. Heap ◽  
A.M. Smith ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Column Density ◽  
Neutral Hydrogen ◽  
Local Interstellar Medium ◽  
Hydrogen Column Density

scholarly journals Massive stars shaping the ISM: H I holes and shells in nearby galaxies

1999 ◽  
Vol 193 ◽  
pp. 636-644
Author(s):  
Elias Brinks ◽  
Fabian Walter
Keyword(s):  
Interstellar Medium ◽  
Dwarf Galaxy ◽  
Massive Stars ◽  
Neutral Hydrogen ◽  
Neutral Medium ◽  
Stellar Winds ◽  
X Ray ◽  
Left Behind ◽  
Neutral Gas ◽  
Nearby Galaxies

Neutral hydrogen (H I) is a magnificent tool when studying the structure of the interstellar medium (ISM) as it is relatively easily observable and can be mapped at good spatial and velocity resolution with modern instruments. Moreover, it traces the cool (∼ 100 K) and warm (∼ 5000 K) neutral gas which together make up about 60%, or the bulk, of the ISM. The currently accepted picture is that stellar winds and subsequent supernovae are the origin for the clearly defined holes or bubbles within the more or less smooth neutral medium. The H I can therefore serve indirectly as a tracer of the hot interstellar medium (HIM) left behind after the most massive stars within an OB association have gone off as supernovae. A splendid example is the dwarf galaxy IC 2574 for which we discuss H I, optical and X-ray observations.

scholarly journals Search for HI Bubbles Around WR Stars: WR 149

1996 ◽  
Vol 169 ◽  
pp. 619-620
Author(s):  
C. Cappa de Nicolau ◽  
V.S. Niemela ◽  
U. Herbstmeier ◽  
B. Koribalski
Keyword(s):  
Interstellar Medium ◽  
Neutral Hydrogen ◽  
Gas Bubbles ◽  
Stellar Winds ◽  
Hydrogen Distribution ◽  
Neutral Gas ◽  
Rayet Star

The interaction of strong stellar winds with the interstellar medium creates large cavities or interstellar bubbles surrounded by expanding outer shells. 21-cm line (HI) observations have revealed the presence of such neutral gas bubbles around several WR stars (e.g. Niemela & Cappa de Nicolau 1991 and references therein; Dubner et al. 1992).Continuing our search for HI bubbles around WR stars, we have analyzed the neutral hydrogen distribution in the vicinity of the Wolf-Rayet star WR149, a highly reddened WN6-7 star located at 6.5 kpc in the direction (l,b) = (89.°53,+0.°65).

scholarly journals Galactic neutral hydrogen and the magnetic ISM foreground

2017 ◽  
Vol 12 (S333) ◽  
pp. 146-150
Author(s):  
S.E. Clark
Keyword(s):  
Interstellar Medium ◽  
Dynamic Range ◽  
Low Frequency ◽  
Neutral Hydrogen ◽  
Depth Resolution ◽  
High Dynamic Range ◽  
Neutral Gas ◽  
High Dynamic ◽  
New Generation ◽  
The Relationship

AbstractThe interstellar medium is suffused with magnetic fields, which inform the shape of structures in the diffuse gas. Recent high-dynamic range observations of Galactic neutral hydrogen, combined with novel data analysis techniques, have revealed a deep link between the morphology of neutral gas and the ambient magnetic field. At the same time, an observational revolution is underway in low-frequency radio polarimetry, driven in part by the need to characterize foregrounds to the cosmological 21-cm signal. A new generation of experiments, capable of high angular and Faraday depth resolution, are revealing complex filamentary structures in diffuse polarization. The relationship between filamentary structures observed in radio-polarimetric data and those observed in atomic hydrogen is not yet well understood. Multiwavelength observations will enable new insights into the magnetic interstellar medium across phases.

scholarly journals The ultraviolet background (intergalactic gas, the Galaxy, and subcosmic rays)

1970 ◽  
Vol 36 ◽  
pp. 341-348
Author(s):  
V. G. Kurt ◽  
R. A. Sunyaev
Keyword(s):  
Interstellar Medium ◽  
Background Radiation ◽  
Neutral Hydrogen ◽  
Exchange Interactions ◽  
List Type ◽  
X Rays ◽  
Intergalactic Gas ◽  
Hydrogen Atoms ◽  
Uv Spectrum ◽  
The Galaxy

(1)Observations. – A survey is made of observations of the background radiation at UV wavelengths from above the atmosphere. Sources of the background radiation and ways of determining the extragalactic component of the background are discussed. Future observations are also discussed.(2)Cosmology. – Limits to the properties of the intergalactic gas follow from observations of the UV background. The problem of detecting galaxies at early stages in their evolution is considered.(3)The Galaxy. – Observations and theoretical estimates are given for the integrated brightness of the Galaxy at UV wavelengths beyond the Lyman-α line. Also discussed are the nature of the Lyman-α emission from the Milky Way and the principal ways of constructing the luminosity function of stars in the Galaxy from observations of the integrated UV spectrum.(4)Subcosmic Rays in the Interstellar Medium. – Fast neutral excited hydrogen atoms can be formed from charge-exchange interactions between subcosmic-ray protons and neutral interstellar gas. Upper limits are given to the energy density of subcosmic rays having E ~ 100 keV.(5)Limits on the Background Radiation in the range <912 Å. – The distribution of neutral hydrogen in the peripheries of galaxies allows limits to be obtained for the flux of metagalactic ionising radiation. The heating and ionisation of the interstellar medium by X-rays is considered.

scholarly journals Gas-Dynamical Effects of Star Formation

1958 ◽  
Vol 8 ◽  
pp. 1073-1074
Author(s):  
M. P. Savedoff
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Neutral Hydrogen ◽  
Limited Range ◽  
Gas Pressure ◽  
Mass Motion ◽  
Motion Field ◽  
Recoil Momentum ◽  
One Dimensional ◽  
Dimensional Flow

At the Second Symposium, various contributors discussed the possibility that star formation might provide the energy to maintain the motion field in the interstellar medium. Although Oort and Spitzer emphasized the importance of the recoil momentum produced by the gradual ionization of the surrounding gas, the important effect appears to be the gas pressure itself when the ionized region is enclosed by the surrounding gas. Indeed, Kahn has shown (for one-dimensional flow into a vacuum) that the recoil momentum is inefficient in producing mass motion; only a limited range in photon fluxes result in acceleration of neutral hydrogen.

Sign in / Sign up

Export Citation Format

Share Document