Studies of the interstellar medium in the inner galaxy at 21 centimeters

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5710524

Garwood, R W

The results from a VLA snapshot survey of the galactic plane in the longitude range 0{degree} {le} l {le} 90{degree} at 1.5 GHz are presented. The positions and peak and total flux densities of 471 sources were measured. The survey is sensitive to sources smaller than about 40 . The resolution is 4 . An excess number of sources above that expected from extragalactic source counts is seen for l < 40{degree} at all flux-density intervals. This excess is primarily due to galactic sources associated with radio recombination line sources. Twenty-one of the brightest compact sources found in the continuum survey are used as background sources for a 21-cm H I absorption survey. The 21-cm velocity-averaged absorption coefficient is calculated as a function of galactocentric radius. This quantity decreases toward the galactic center from a solar neighborhood value of 5 km s{sup {minus}1}kpd{sup {minus}1}, in agreement with high-latitude absorption surveys, to roughly one-fourth of this value within 2 kpc from the galactic center. The results of a search for infrared counterparts to the compact sources found in the VLA survey are presented. Nine red sources likely to be associated with a radio source were found. Most of these seem to be moderately hot, distant main-sequence stars and their associated H II regions.

• Research Organization: Minnesota Univ., Minneapolis, MN (USA)
• OSTI ID: 5710524
• Country of Publication: United States
• Language: English

Related Subjects

640102 -- Astrophysics &amp; Cosmology-- Stars &amp; Quasi-Stellar
Radio &amp; X-Ray Sources
640105* -- Astrophysics &amp; Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BACKGROUND RADIATION
COSMIC RADIO SOURCES
GALAXIES
H1 REGIONS
H2 REGIONS
INFRARED SPECTRA
INTERSTELLAR SPACE
MAIN SEQUENCE STARS
MILKY WAY
RADIATIONS
SPACE
SPECTRA
STARS