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Ultraviolet photometry from the Orbiting Astronomical Observatory. XX - The ultraviolet extinction bumpUltraviolet extinction bumps are investigated in the interstellar extinction curves between 1800 and 3600 A for 36 stars which have (B-V) excesses ranging from 0.03 to 0.55 and are mostly confined to the brighter OB associations distributed along the galactic plane. Each extinction curve is found to have a broad bump which peaks near 2175 A and whose position and profile appear to be constant among all the stars. It is shown that the bump is probably interstellar in origin and that the constancy of its position and shape places such severe restrictions on grain geometrical parameters that classical scattering theory cannot be used to explain the feature unless the dust grains in widely separated regions of space and with very different physical conditions are assumed to have nearly identical size and shape distributions. Three extinction curves which extend to 1100 A are examined and found to have the same general characteristics as the others. Several extinction curves are analyzed for fine structure, but no convincing evidence is found in the present interval. Some processes are discussed which may be responsible for the bumps.
Document ID
19750053855
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Savage, B. D.
Date Acquired
August 8, 2013
Publication Date
July 1, 1975
Publication Information
Publication: Astrophysical Journal
Volume: 199
Subject Category
Astrophysics
Accession Number
75A37927
Funding Number(s)
CONTRACT_GRANT: NAS5-1348
Distribution Limits
Public
Copyright
Other

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