Astronomy and Astrophysics – Astrophysics
Scientific paper
Sep 1990
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990phdt........23m&link_type=abstract
Ph.D. Thesis Queens Univ., Kingston (Ontario). Dept. of Physics.
Astronomy and Astrophysics
Astrophysics
2
Galactic Structure, Infrared Astronomy Satellite, Infrared Sources (Astronomy), Infrared Spectra, Milky Way Galaxy, Stellar Spectra, Astronomical Catalogs, Astrophysics, Infrared Astronomy, Star Formation
Scientific paper
Criteria are presented which identify 2298 objects in the Infrared Astronomical (IRAS) Satellite Point Source Catalog, of which 77 percent are estimated to be HII regions. The 2298 point sources are then used to study the structure of the Milky Way. The results of this study confirm the notion that the galactic plane undulates about a mean plane and that the sun is positioned above the mean plane. A simple model is derived to explain the range of infrared spectral shapes of the IRAS point sources. It is found that a model with a stellar source at the center of a small (less than 1-2 pc in radius) dust cloud, where the average temperature of the cloud is varied, can explain the range of shapes of the IRAS spectra. In this model a power-law dependence on radius is assumed for both temperature and gas (and dust) density. The model predicts that embedded early B type stars will have steeper IRAS spectra than embedded O type stars under similar cloud conditions. Radio observations of 8 of the 24 IRAS sources with the steepest spectra were taken to determine the spectral type(s) of the exciting star(s). Using this data, other radio data from the literature, and estimated distances to the sources, the spectral types of 14 IRAS point sources with steep infrared spectra are determined.
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