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IRAS surface brightness maps of reflection nebulae in the PleiadesSurface brightness maps at 12, 25, 60, and 100 microns were made of a 2.5 deg x 2.5 deg area of the reflection nebulae in the Pleiades by coadding IRAS scans of this region. Emission is seen surrounding 17 Tau, 20 Tau, 23 Tau, and 25 Tau in all four bands, coextensive with the visible reflection nebulosity, and extending as far as 30 arcminutes from the illuminating stars. The infrared energy distributions of the nebulae peak in the 100 micron band, but up to 40 percent of the total infrared power lies in the 12 and 25 micron bands. The brightness of the 12 and 25 micron emission and the absence of temperature gradients at these wavelengths are inconsistent with the predictions of equilibrium thermal emission models. The emission at these wavelengths appears to be the result of micron nonequilibrium emission from very small grains, or from molecules consisting of 10-100 carbon atoms, which have been excited by ultraviolet radiation from the illuminating stars.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Castelaz, Michael W.
(NASA Ames Research Center Moffett Field, CA, United States)
Werner, M. W.
(NASA Ames Research Center Moffett Field, CA, United States)
Sellgren, K.
(Hawaii, University Honolulu, United States)
Date Acquired
August 13, 2013
Publication Date
February 15, 1987
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 313
ISSN: 0004-637X
Subject Category
Accession Number
Distribution Limits

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