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Compact infrared sources : NGC 7538 and the galactic center

Citation

Willner, Steven Paul (1976) Compact infrared sources : NGC 7538 and the galactic center. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-08252008-153611

Abstract

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Three infrared and radio sources in NGC 7538 have been observed from 8 to 13 [...] with 1% spectral and 5" spatial resolution. The very small southern source shows a deep silicate absorption feature at 9.7 [...] while the northern extended source shows little or no silicate absorption, but has a 12.8-[...] emission line from Ne II. The data imply that the compact source has a gas to dust ratio of 75 inside the ionized region. The extended source only 10" away has a gas to dust ratio implied by the 10-[...] data alone of 3 x 10[...], but the true ratio must be much lower to account for published 20-[...] measurements.

A revised 10-[...] map of the Galactic center with 2[...]3 resolution, broadband photometry of individual sources from 1.2 to 20 [...], and 8 to 13-[...] photometry of individual sources with 1% spectral resolution have been obtained. The principal conclusions of this study are: (1) The five sources with the bluest energy distributions between 1.6 and 3.5 [...] are stars or star clusters. The brightest has a luminosity of 10[...] L[...] while the other four have luminosities of about 10[...] L[...]. (2) There is extended emission from ionized gas and dust. (3) The density of ionized gas in the discrete 10-[...] sources is no higher than that in the extended source. (4) There is at least one compact source that is not associated with the others and has a different energy distribution. (5) Most of the extinction toward the sources observed is interstellar and is moderately uniform. The visual extinction is about 28 magnitudes, and the 9.7-[...] silicate extinction is about 3.7 magnitudes.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astronomy
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Becklin, Eric E. (advisor)
  • Neugebauer, Gerry (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:29 January 1976
Record Number:CaltechETD:etd-08252008-153611
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-08252008-153611
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3225
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:09 Sep 2008
Last Modified:26 Dec 2012 02:58

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