The Unidentified Infrared Bands in the Diffuse Interstellar Medium across the Galaxy Based on theInfrared Telescope in SpaceMid‐Infrared Spectrometer Observation

2004 ◽  
Vol 609 (1) ◽  
pp. 203-219 ◽  
Author(s):  
Itsuki Sakon ◽  
Takashi Onaka ◽  
Daisuke Ishihara ◽  
Takafumi Ootsubo ◽  
Issei Yamamura ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
The Galaxy ◽  
Infrared Spectrometer

Erratum: “The Unidentified Infrared Bands in the Diffuse Interstellar Medium across the Galaxy Based on theInfrared Telescope in SpaceMid‐Infrared Spectrometer Observation” (ApJ, 609, 203 [2004])

2005 ◽  
Vol 625 (2) ◽  
pp. 1062-1062
Author(s):  
Itsuki Sakon ◽  
Takashi Onaka ◽  
Daisuke Ishihara ◽  
Takafumi Ootsubo ◽  
Issei Yamamura ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
The Galaxy ◽  
Infrared Spectrometer

scholarly journals Abundances in the Gaseous Galactic Halo

1998 ◽  
Vol 11 (1) ◽  
pp. 86-89
Author(s):  
Ulysses J. Sofia
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
High Velocity ◽  
Galactic Halo ◽  
Solar Neighborhood ◽  
Local Interstellar Medium ◽  
The Galaxy ◽  
Metal Abundances ◽  
High Velocity Clouds

Abstract The well measured gas-phase abundances in the low halo suggest that this region of the Galaxy has total (gas plus dust) metal abundances which are close to those in the solar neighborhood. The gas-phase abundances in the halo are generally higher than those seen in the disk, however, this affect is likely due to the destruction of dust in the halo clouds. Observations of high velocity clouds (HVCs) in the halo suggest that these clouds have metal abundances which are substantially lower than those measured for the local interstellar medium. These determinations, however, are often of lower quality than those for the low halo because of uncertainties in the hydrogen abundances along the sightlines, in the incorporation of elements into dust, and in the partial ionization of the clouds.

scholarly journals Astrophysical MHD turbulence: confluence of observations, simulations, and theory

2012 ◽  
Vol 8 (S294) ◽  
pp. 325-336 ◽  
Author(s):  
Blakesley Burkhart ◽  
Alex Lazarian
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Magnetic Reconnection ◽  
Particle Transport ◽  
Recent Progress ◽  
Critical Component ◽  
Dynamo Theory ◽  
Mhd Turbulence ◽  
The Galaxy

AbstractMagnetohydrodynamic (MHD) turbulence is a critical component of the current paradigms of star formation, dynamo theory, particle transport, magnetic reconnection and evolution of the ISM. In order to gain understanding of how MHD turbulence regulates processes in the Galaxy, a confluence of numerics, observations and theory must be imployed. In these proceedings we review recent progress that has been made on the connections between theoretical, numerical, and observational understanding of MHD turbulence as it applies to both the neutral and ionized interstellar medium.

scholarly journals DIBs, Interstellar Dust, and Extinction

2013 ◽  
Vol 9 (S297) ◽  
pp. 147-152 ◽  
Author(s):  
G. C. Clayton
Keyword(s):  
Interstellar Medium ◽  
Interstellar Dust ◽  
Dust Grains ◽  
Weak Correlation ◽  
Interstellar Clouds ◽  
The Galaxy ◽  
The Relationship

AbstractThe relationship between DIBs and dust is still unknown. The correlation between reddening and DIB strength means that the DIBs are mixed in with the dust and gas in interstellar clouds. The DIBs are relatively stronger in the diffuse interstellar medium than in dense clouds. There is only a weak correlation between the DIBs and the UV extinction parameters including the 2175 Å bump strength and the far-UV rise. In addition, the bump dust grains are sometimes polarized, while the DIBs are not. However, observations of DIBs in the SMC show that when the 2175 Å bump is weak or missing so are the DIBs. Two of the four sightlines that deviate strongly from the CCM UV extinction in the Galaxy show weak DIBs.

scholarly journals Unidentified infrared bands in the interstellar medium across the Galaxy

2003 ◽  
Vol 405 (3) ◽  
pp. 999-1012 ◽  
Author(s):  
J. Kahanpää ◽  
K. Mattila ◽  
K. Lehtinen ◽  
C. Leinert ◽  
D. Lemke
Keyword(s):  
Interstellar Medium ◽  
The Galaxy

Pulsars and Interstellar Scintillations

2000 ◽  
Vol 177 ◽  
pp. 539-544
Author(s):  
Y. Gupta
Keyword(s):  
Interstellar Medium ◽  
Electron Density ◽  
Density Fluctuations ◽  
Current Understanding ◽  
Pulsar Emission ◽  
The Galaxy ◽  
Electron Density Fluctuations

AbstractIn this paper, I review our current understanding of interstellar scintillations (ISS) of pulsars. The emphasis is on new results that have appeared during the last five years. The topics covered include (i) review of the understanding of refractive ISS (ii) the shape of the spectrum of electron density fluctuations in the interstellar medium (iii) the distribution of scattering plasma in the Galaxy (iv) resolving pulsar emission regions using ISS and (v) ISS and pulsar velocities.

scholarly journals What do Gamma Rays tell us about the ISM?: New Insight from the Compton Observatory

1996 ◽  
Vol 169 ◽  
pp. 437-446 ◽  
Author(s):  
Hans Bloemen
Keyword(s):  
Interstellar Medium ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Line Emission ◽  
Cosmic Ray ◽  
Gamma Ray Astronomy ◽  
Early Results ◽  
The Galaxy ◽  
Γ Ray ◽  
Insight Into

Gamma-ray astronomy has become a rich field of research and matured significantly since the launch of NASA's Compton Gamma Ray Observatory in April 1991. Studies of the diffuse γ-ray emission of the Galaxy can now be performed in far more detail and extended into the MeV regime, including both continuum and line emission. These studies provide unique insight into various aspects of the interstellar medium, in particular of the cosmic-ray component. This paper gives a brief review on the diffuse Galactic γ-ray emission and summarizes early results and prospects from the Compton Observatory.

scholarly journals Nuclear molecular gas in the Virgo Cluster S0 galaxy NGC 4710

1993 ◽  
Vol 153 ◽  
pp. 439-440
Author(s):  
J.M. Wrobel ◽  
J.D.P. Kenney
Keyword(s):  
Interstellar Medium ◽  
Emission Line ◽  
Optical Emission ◽  
Virgo Cluster ◽  
Gas Analysis ◽  
Molecular Gas ◽  
Star Forming ◽  
The Galaxy

The CO(J=1→0) emission from NGC 4710, a star–forming S0 galaxy in the Virgo Cluster, was synthesized with spatial and velocity resolutions of 7″ and 26 km s—1, respectively. The CO shows a compact morphology and co–rotates with the galaxy's stars and nuclear optical emission line gas. Analysis of the CO distribution and kinematics indicates that the nuclear molecular gas is probably gravitationally unstable, and this may explain why the galaxy is presently forming stars. Four possible origins for the nuclear molecular gas are considered. An origin via bulge star ejecta being deposited into a residual interstellar medium is favored.

scholarly journals The O stars: optical review

1979 ◽  
Vol 83 ◽  
pp. 1-22
Author(s):  
J. B. Hutchings
Keyword(s):  
Neutron Star ◽  
Interstellar Medium ◽  
Mass Loss ◽  
Large Fraction ◽  
Significant Fraction ◽  
High Mass ◽  
X Ray ◽  
The Galaxy ◽  
High Mass Loss ◽  
Rough Outline

I would like to start with a quick overview of the O stars - their significance and role in the galaxy and in astrophysics - just to remind ourselves of why we are here and what we hope to talk about. In Table 1 I show a rough outline of the contribution of O stars to what happens in the galaxy as a whole. Because of their extreme luminosity, they contribute a large fraction of the radiation of the galaxy, while forming a very tiny group of objects and mass. Because of their short lifetime they are a population that has gone through 104 generations in the life of the galaxy. Their high mass loss rates may account for a large fraction of the new matter injected into the interstellar medium, and they probably power some significant fraction of the hard X-ray sources in the galaxy, by virtue of the fact that a companion can become a neutron star a) without disrupting the binary and b) while the companion is still a mass losing O star.

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.

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