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Ultraviolet, optical, and infrared observations of the high-latitude molecular cloud toward HD 210121Low-resolution UV spectra of the B3 V star HD 210121, located behind the high-latitude molecular cloud DBB 80, yield an extinction curve exhibiting a far-UV rise that is among the steepest known. The apparently simple line of sight affords an excellent opportunity for investigating the absorption and emission characteristics of a single, isolated interstellar cloud characterized by extreme UV extinction. The low ratios of the IRAS bands with respect to I(100 microns) suggest that the radiation field incident on the cloud is lower than the average interstellar field, with further attenuation of the field within the cloud. The apparent relative enhancement of I(12 microns) compared with models of dust emission, and the extremely steep far-UV extinction together are consistent with the presence of an enhanced population of very small grains; the normal calcium depletion suggests that there has been little wholesale grain destruction. The steep far-UV extinction may help to explain the relatively high abundances of CO and CN. The disagreement in density for this cloud inferred from C2 absorption versus that inferred from CO emission may be due in part to clumping in the gas sample by the radio beams.
Document ID
19920061193
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Welty, Daniel E.
(Chicago, University IL, United States)
Fowler, James R.
(New Mexico State University; Apache Point Observatory, Sunspot, United States)
Date Acquired
August 15, 2013
Publication Date
July 1, 1992
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 393
Issue: 1 Ju
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
92A43817
Funding Number(s)
CONTRACT_GRANT: NAG5-1303
CONTRACT_GRANT: NAG5-286
CONTRACT_GRANT: NAG5-704
CONTRACT_GRANT: NAG5-1434
Distribution Limits
Public
Copyright
Other

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