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The Infrared Reflection Nebula Around the Protostellar System in S140We have studied the protostellar system in S140 at 2.2, 3.1 and 3.45 microns using a 128x128 InSb array at the Lick Observatory 3m telescope. Besides the protostellar sources, the data reveal a bright infrared reflection nebula. We have developed a simple model of this region and derived the physical conditions. IRSI is surrounded by a dense dusty disk viewed almost edge-on. Photons leaking out through the poles illuminate almost directly north and south the inner edge of a surrounding shell of molecular gas, Analysis of the observed colors and intensities of the NIR light, using Mie scattering theory, reveal that the dust grains in the molecular cloud are somewhat larger than in the general diffuse interstellar medium. Moreover, the incident light has a "cool" color temperature, approximately equals 800K, and likely originates from a dust photosphere close to the protostar. Finally, we find little H2O ice associated with the dusty disk around IRSI. Most of the 3.1 micron ice extinction arises instead from cool intervening molecular cloud material. We have compared our infrared dust observations with millimeter and radio observations of molecular gas associated with this region. The large scale structure observable in the molecular gas is indicative of the interaction between the protostellar wind and the surrounding molecular cloud rather than the geometry of the protostellar disk. We conclude that S140 is a young blister formed by this outflow on the side of a molecular cloud and viewed edge-on.
Document ID
20010047006
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Harker, D.
(NASA Ames Research Center Moffett Field, CA United States)
Bregman, J.
(NASA Ames Research Center Moffett Field, CA United States)
Tielens, A. G. G. M.
(NASA Ames Research Center Moffett Field, CA United States)
Temi, P.
(NASA Ames Research Center Moffett Field, CA United States)
Rank, D.
(NASA Ames Research Center Moffett Field, CA United States)
Morrison, David
Date Acquired
August 20, 2013
Publication Date
January 1, 1994
Subject Category
Astrophysics
Funding Number(s)
PROJECT: RTOP 352-02-03
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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