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Observations of Absorption Lines from Highly Ionized AtomsIn the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. fewX 0.001/cucm) existing at coronal temperatures, 5.3 or = log T or = 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity 9v or = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic uv radiation from very hot, dward stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.
Document ID
19850007253
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Jenkins, E. B.
(Princeton Univ. Observatory NJ, United States)
Date Acquired
August 12, 2013
Publication Date
November 1, 1984
Publication Information
Publication: NASA. Goddard Space Flight Center Local Interstellar Medium, No. 81
Subject Category
Astrophysics
Accession Number
85N15562
Funding Number(s)
CONTRACT_GRANT: NAGW-477
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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