scholarly journals Modern view of the warm ionized medium

2012 ◽  
Vol 10 (H16) ◽  
pp. 574-575 ◽  
Author(s):  
A. Hill ◽  
R. Reynolds ◽  
L. Haffner ◽  
K. Wood ◽  
G. Madsen
Keyword(s):  
Interstellar Medium ◽  
High Latitude ◽  
Milky Way ◽  
Scattered Light ◽  
Observational Evidence ◽  
Distinct Component ◽  
Modern View ◽  
Hα Emission ◽  
Warm Ionized Medium

AbstractWe review the observational evidence that the warm ionized medium (WIM) is a major and physically distinct component of the Galactic interstellar medium. Although up to ~ 20% of the faint, high-latitude Hα emission in the Milky Way may be scattered light emitted in midplane Hii regions, recent scattered light models do not effectively challenge the well-established properties of the WIM.

Interstellar Cirrus Observed in Balmer Hα

1998 ◽  
Vol 179 ◽  
pp. 184-185
Author(s):  
P.R. McCullough
Keyword(s):  
Interstellar Medium ◽  
Milky Way ◽  
Dust Emission ◽  
Cosmic Background ◽  
Angular Scale ◽  
Hα Emission ◽  
Warm Ionized Medium ◽  
New View

We present Hα images with 0.1° resolution and fields of view larger than 10°. In some regions of the sky, the Balmer Hα emission is correlated positively with IRAS 100 μm emission. Observations of such sensitivity and angular scale as these provide a new view of the interstellar medium of our Galaxy (see also Dennison et al., this volume, p. 182) and may allow us to distinguish between Galactic foreground and cosmic background for both the free-free emission and the thermal dust emission associated with the warm ionized medium of the Milky Way.

scholarly journals A Warm Magnetoactive Plasma in a Large Volume of Space

1984 ◽  
Vol 81 ◽  
pp. 263-267
Author(s):  
Carl Heiles
Keyword(s):  
Magnetic Field ◽  
Interstellar Medium ◽  
Emission Line ◽  
Faraday Rotation ◽  
Large Volume ◽  
Magnetoactive Plasma ◽  
Zeeman Splitting ◽  
Observational Evidence ◽  
General Direction ◽  
Hα Emission

This paper will show that a diffuse ionized warm gas fills a large volume of space in the general direction of Radio Loop II. There are three types of observational evidence: Faraday rotation measures (RM's) of extragalactic sources; emission measures (EM's) derived from the Hα emission line in the diffuse interstellar medium; and magnetic field strengths in HI clouds derived from Zeeman splitting observations.

3He in the Milky Way Interstellar Medium: Abundance Determinations

1999 ◽  
Vol 510 (2) ◽  
pp. 759-783 ◽  
Author(s):  
Dana S. Balser ◽  
T. M. Bania ◽  
Robert T. Rood ◽  
T. L. Wilson
Keyword(s):  
Interstellar Medium ◽  
Milky Way

Radio recombination line observations towards Spitzer infrared bubbles with the TianMa radio telescope

2019 ◽  
Vol 489 (4) ◽  
pp. 4862-4874
Author(s):  
L G Hou ◽  
X Y Gao
Keyword(s):  
Radio Telescope ◽  
Detection Rate ◽  
Milky Way ◽  
Absorption Method ◽  
Recombination Line ◽  
Ionized Gas ◽  
Radio Recombination Line ◽  
Warm Ionized Medium

ABSTRACT Many of the Spitzer infrared bubbles identified by the Milky Way Project (MWP) are suggested to be $\rm{H \small {II}} $ regions in nature. More than 70 per cent of the ∼5000 known bubbles do not have radio recombination line (RRL) observations, hence have not been confirmed as $\rm{H \small {II}} $ regions. A systematic RRL survey should be helpful to identify the nature of the bubbles. With the Shanghai TianMa 65-m radio telescope, we searched for RRLs towards 216 selected Spitzer bubbles by simultaneously observing 19 RRLs in the C band (4–8 GHz). RRLs are detected in the directions of 75 of the 216 targets. 31 of the 75 RRL sources are classified as new detections, which are possibly from new $\rm{H \small {II}} $ regions or diffuse warm ionized medium; 36 of them are probably from the outskirts of nearby bright $\rm{H \small {II}} $ regions, rather than bubble-encircled ionized gas; and the detected RRLs towards 8 bubbles are identified from known $\rm{H \small {II}} $ regions. For 58 of the 75 RRL sources, we obtained their distances after resolving the kinematic distance ambiguity by combining the results of the H2CO absorption method, the $\rm{H \small {I}} $ emission/absorption method, and the $\rm{H \small {I}} $ self-absorption method. The low detection rate of new $\rm{H \small {II}} $ regions implies that a number of MWP bubbles in the DR1 catalogue are too faint if they are $\rm{H \small {II}} $ regions.

scholarly journals Kinematical & Chemical Characteristics of the Thin and Thick Disks

2008 ◽  
Vol 4 (S254) ◽  
pp. 179-190 ◽  
Author(s):  
Rosemary F. G. Wyse
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Observational Evidence ◽  
Chemical Characteristics ◽  
Chemical Abundance ◽  
The Galaxy ◽  
History Of ◽  
Thin And Thick Disks ◽  
Thick Disks

AbstractI discuss how the chemical abundance distributions, kinematics and age distributions of stars in the thin and thick disks of the Galaxy can be used to decipher the merger history of the Milky Way, a typical large galaxy. The observational evidence points to a rather quiescent past merging history, unusual in the context of the ‘consensus’ cold-dark-matter cosmology favoured from observations of structure on scales larger than individual galaxies.

scholarly journals Magnetohydrodynamic Turbulence at High-Latitude Regions of the Milky Way

2011 ◽  
Vol 0 (0) ◽  
Author(s):  
Nickolas Pingel ◽  
Snežana Stanimirović ◽  
Min Young-Lee
Keyword(s):  
High Latitude ◽  
Milky Way ◽  
Magnetohydrodynamic Turbulence

scholarly journals High-Velocity Clouds and the Local Group

2004 ◽  
Vol 217 ◽  
pp. 2-11 ◽  
Author(s):  
B. P. Wakker
Keyword(s):  
High Velocity ◽  
Milky Way ◽  
Local Group ◽  
Current Data ◽  
The Other ◽  
Hot Gas ◽  
Neutral Gas ◽  
Hα Emission ◽  
M 31 ◽  
High Velocity Clouds

I examine some of the evidence relevant to the idea that high-velocity clouds (HVCs) are gas clouds distributed throughout the Local Group, as proposed by Blitz et al. (1999) and Braun & Burton (1999). This model makes several predictions: a) the clouds have low metallicities; b) there should be no detectable Hα emission; c) analogues near other galaxies should exist; and d) many faint HVCs in the region around M 31 can be found. Low metallicities are indeed found in several HVCs, although they are also expected in several other models. Hα emission detected in most HVCs and, when examined more closely, distant (D>200 kpc) HVCs should be almost fully ionized, implying that most HVCs with H I must lie near the Milky Way. No clear extragalactic analogues have been found, even though the current data appear sensitive enough. The final prediction (d) has not yet been tested. on balance there appears to be no strong evidence for neutral gas clouds distributed throughout the Local Group, but there may be many such clouds within 100 or so kpc from the Milky Way (and M31). on the other hand, some (but not all) of the high-velocity O VI recently discovered may originate in hot gas distributed throughout the Local Group.

scholarly journals The interstellar medium of the Magellanic Clouds from absorption lines

1991 ◽  
Vol 148 ◽  
pp. 401-406 ◽  
Author(s):  
Klaas S. De Boer
Keyword(s):  
Interstellar Medium ◽  
Absorption Line ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Absorption Lines ◽  
Small Magellanic Cloud ◽  
General Aspects

General aspects of ISM studies using absorption line studies are given and available data are reviewed. Topics are: galactic foreground gas, individual fields in the Magellanic Clouds (MCs) and MC coronae. Overall investigations are discussed. It is demonstrated that the metals in the gas of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are a factor of 3 and 10, respectively, in abundance below solar levels. The depletion pattern in the LMC is similar to that of the Milky Way.

scholarly journals Enrichment by Wolf-Rayet Stars and Other Massive Stars in Gas, Dust and Energy

1991 ◽  
Vol 143 ◽  
pp. 323-334
Author(s):  
Martin Cohen
Keyword(s):  
Interstellar Medium ◽  
Infrared Spectra ◽  
Stellar Wind ◽  
Massive Stars ◽  
Observational Evidence ◽  
Radiative Energy ◽  
New Members ◽  
Hot Gas ◽  
Sn 1987A ◽  
Dust Mass

I update previous estimates of the separate contributions for radiative energy, integrated total stellar wind mass and dust mass from Wolf-Rayet stars and other massive (OBA) stars. In the context of the intriguing dusty WC9 stars, I: (1) discuss the observability (or otherwise) between 0.4 and 23 μm of the condensation route from hot gas to carbon-rich grains; (2) urge caution in the use of 10 μm infrared spectra of these luminous stars to deduce the importance of silicates as a component of the interstellar medium, and (3) speculate on a possible new method for discovering new members of this relatively rare subtype based on IRAS Low Resolution Spectra. I review the observational evidence for dust condensation around SN 1987A.

scholarly journals Chemical Inhomogeneities in Galaxies

1977 ◽  
Vol 45 ◽  
pp. 67-71 ◽  
Author(s):  
M. G. Edmunds
Keyword(s):  
Interstellar Medium ◽  
Chemical Evolution ◽  
Galactic Disk ◽  
Observational Evidence ◽  
Galactic Evolution ◽  
Length Scale ◽  
Galactic Chemical Evolution ◽  
Large Length ◽  
Large Length Scale

The local chemical inhomogneity of the interstellar medium at a given time is an important factor in models of galactic chemical evolution. It can affect both the G-dwarf metallicity problem (Tinsley 1975, Talbot and Arnett 1973) and the correlation of the abundances of different elements (Tinsley 1976). Observational evidence of abundance gradients in our own Galaxy, and someothergalaxies (summarised by Peimbert 1975, van den Bergh 1975), implies that in homogeneities over a large length scale must be created and survive during galactic evolution. Brief consideration of the mixing of the Galactic disk (e.g. Edmunds 1975, 1976) suggests

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