NEW BACKGROUND INFRARED SOURCES FOR STUDYING THE GALACTIC CENTER'S INTERSTELLAR GAS

Water and molecular oxygen are two simple molecules which are not easily observed in the interstellar medium. O2 emissions have yet to be detected from interstellar space, and H2O has been observed only in rather special environments where the interstellar gas has been warmed by embedded infrared sources or by shock waves. This sorry state of affairs does not necessarily reflect a low interstellar abundance for these species, but rather is a consequence of the very high abundance of O2 and H2O within our own atmosphere: strong atmospheric absorption lines make it extremely difficult to carry out observations of water and molecular oxygen emissions using ground-based or even airborne telescopes. Future observations from two orbiting telescopes scheduled for launch in the coming five years - the Infrared Space Observatory (ISO) and the Submillimeter Wave Astronomy Satellite (SWAS) - promise to improve radically the observational data on H2O and O2.

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A search for interstellar gas-phase CO2

Symposium - International Astronomical Union ◽

10.1017/s0074180900009566 ◽

1997 ◽

Vol 178 ◽

pp. 401-404 ◽

Cited By ~ 2

Author(s):

E.F. Van Dishoeck ◽

F.P. Helmich

Keyword(s):

Gas Phase ◽

Short Wavelength ◽

High Abundance ◽

Interstellar Space ◽

Interstellar Gas ◽

Earth’S Atmosphere ◽

Earth's Atmosphere ◽

Bending Modes ◽

Infrared Sources ◽

Asymmetric Stretch

CO2 is one of the simplest carbon- and oxygen-containing molecules, for which little is known in interstellar space, because of its high abundance in the Earth's atmosphere. Only indirect searches of the chemically related HOCO+ ion have been possible from the ground (Thaddeus et al. 1981; Minh et al. 1988, 1991). The ISO Short Wavelength Spectrometer (SWS) (de Graauw et al. 1996a) opens up the possibility to search for the infraredactive asymmetric stretch and bending modes of gas-phase CO2 around 4.3 and 15.0 μm toward bright infrared sources.

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Background Infrared Sources for Studying the Galactic Center’s Interstellar Gas

The Astrophysical Journal ◽

10.3847/1538-4357/aafedc ◽

2019 ◽

Vol 872 (1) ◽

pp. 103 ◽

Cited By ~ 8

Author(s):

T. R. Geballe ◽

E. Lambrides ◽

B. Schlegelmilch ◽

S. C. C. Yeh ◽

M. Goto ◽

...

Keyword(s):

Interstellar Gas ◽

Infrared Sources

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Interstellar gas in the central region of the Galaxy

Symposium - International Astronomical Union ◽

10.1017/s0074180900101032 ◽

1967 ◽

Vol 31 ◽

pp. 239-251 ◽

Cited By ~ 3

Author(s):

F. J. Kerr

Keyword(s):

Central Region ◽

Galactic Plane ◽

Neutral Hydrogen ◽

Continuum Emission ◽

Galactic Centre ◽

Interstellar Gas ◽

Hydrogen Recombination ◽

The Galaxy ◽

Centre Region ◽

The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

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Supernovae and interstellar gas dynamics

Symposium - International Astronomical Union ◽

10.1017/s0074180900100774 ◽

1967 ◽

Vol 31 ◽

pp. 117-119

Author(s):

F. D. Kahn ◽

L. Woltjer

Keyword(s):

Lower Limit ◽

High Velocity ◽

Gas Dynamics ◽

Interstellar Cloud ◽

Interstellar Gas ◽

Random Motions ◽

Relativistic Particles

The efficiency of the transfer of energy from supernovae into interstellar cloud motions is investigated. A lower limit of about 0·002 is obtained, but values near 0·01 are more likely. Taking all uncertainties in the theory and observations into account, the energy per supernova, in the form of relativistic particles or high-velocity matter, needed to maintain the random motions in the interstellar gas is estimated as 1051·4±1ergs.

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Remarks on the diffuse interstellar lines

Symposium - International Astronomical Union ◽

10.1017/s0074180900100750 ◽

1967 ◽

Vol 31 ◽

pp. 91-93 ◽

Cited By ~ 4

Author(s):

G. Herzberg

Keyword(s):

Hydrogen Atoms ◽

Interstellar Gas

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.

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