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Variable extinction in HD 45677 and the evolution of dust grains in pre-main-sequence disksChanges in the UV extinction and IR emission were sought in the Herbig Ae/Be star candidate HD 45677 (= FS CMa) by comparing UV, optical, and IR observations made approximately 10 yr apart. HD 45677 varied significantly, becoming more than 50% brighter in the UV and optical than it was a decade ago. A comparison of the observations between epochs indicates that if the variations are due to changes in dust obscuration, the dust acts as a gray absorber into the near-IR and must be depleted in grains smaller than 1 micron. This is similar to the results obtained on the circumstellar disks of stars like Vega and Beta Pic, and suggests that radiation pressure may be responsible for the small-grain depletion. In addition, the total IR flux seems to have declined, indicating a decrease in the total mass of the dust envelope that contributes to the IR emission in this part of the spectrum. Due to the anomalous nature of the extinction, the use of normal extinction curves to deredden the spectral energy distributions of stars with circumstellar dust may lead to significant errors and should be used with great caution.
Document ID
19950039630
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Sitko, Michael L.
(University of Cincinnati, Cincinnati, OH United States)
Halbedel, Elaine M.
(Corralitos Observatory, Las Cruces, NM United States)
Lawrence, Geoffrey F.
(University of Minnesota, Minneapolis, MN United States)
Smith, J. Allyn
(Florida Institute of Technology, Melbourne, FL United States)
Yanow, Ken
(San Diego State University San Diego, CA, United States)
Date Acquired
August 16, 2013
Publication Date
September 10, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 432
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A71229
Funding Number(s)
CONTRACT_GRANT: NAG5-1770
Distribution Limits
Public
Copyright
Other

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