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The excess infrared emission of Herbig Ae/Be stars - Disks or envelopes?It is suggested that the near-IR emission in many Herbig Ae/Be stars arises in surrounding dusty envelopes, rather than circumstellar disks. It is shown that disks around Ae/Be stars are likely to remain optically thick at the required accretion rates. It is proposed that the IR excesses of many Ae/Be stars originate in surrounding dust nebulae instead of circumstellar disks. It is suggested that the near-IR emission of the envelope is enhanced by the same processes that produce anomalous strong continuum emission at temperatures of about 1000 K in reflection nebulae surrounding hot stars. This near-IR emission could be due to small grains transiently heated by UV photons. The dust envelopes could be associated with the primary star or a nearby companion star. Some Ae/Be stars show evidence for the 3.3-6.3-micron emission features seen in reflection nebulae around hot stars, which lends further support to this suggestion.
Document ID
19930050720
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hartmann, Lee
(NASA Headquarters Washington, DC United States)
Kenyon, Scott J.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Calvet, Nuria
(Centro de Investigaciones de Astronomia Merida, Venezuela)
Date Acquired
August 16, 2013
Publication Date
April 10, 1993
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 407
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Funding Number(s)
CONTRACT_GRANT: NAGW-2919
Distribution Limits
Public
Copyright
Other
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