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Ultraviolet illuminated molecular cloud boundaries: Extended (C II) 158 micrometer emission toward L1630The construction of a large scale map of the 158 micrometer C+ line toward the L1630/Orion B molecular cloud, covering an approximately 35' by 45' area which includes the NGC 2024 H II region, zeta-Ori, the reflection nebula NGC 2023, and the Horsehead nebula, is reported. Emission in the C II line is very widespread. The line was detected at levels in excess of a few 0.0001 erg/sq cm/s/sr over almost the entire mapped region. Extended emission associated with the NGC 2024 H II region and its envelope accounts for more than half of the C II flux. Over this approximately 1.5 by 2.5 pc region, the amount of gas phase carbon in the form of C+ is comparable to the amount of carbon in CO. This result, together with the C II distribution implies that C II emission arises on the surface of clumps throughout the cloud rather than in a single layer at the H II region boundary. Away from the H II region, most of the C II emission comes from the western edge of the L1630 cloud and probably results from excitation by external OB stars. The overall extent of the C II emission is comparable to that of millimeter molecular lines but the distributions are different in detail. The difference in C II and molecular line distributions, in particular, the larger extent of the C II emission west of NGC 2024 implies large variations in the ratio of the C II and J = 1 towards 0 intensities. Models of photon dominated regions can explain the relation between C II and CO intensities only if the cloud edges and cloud interior are considered separately. A method for using C II and radio continuum emission to characterize the relationship between OB stars and photon dominated regions is proposed.
Document ID
19950020221
Acquisition Source
Legacy CDMS
Document Type
Preprint (Draft being sent to journal)
Authors
Jaffe, D. T.
(Texas Univ. Austin, TX., United States)
Zhou, S.
(Illinois Univ. Urbana, IL., United States)
Howe, J. E.
(Maryland Univ. College Park, MD., United States)
Herrmann, F.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Madden, S. C.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Poglitsch, A.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Vanderwerf, P. P.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Stacey, G. J.
(Cornell Univ. Ithaca, NY., United States)
Date Acquired
August 16, 2013
Publication Date
June 1, 1994
Subject Category
Astrophysics
Report/Patent Number
MPR-PREPRINT-290
NASA-CR-197958
NAS 1.26:197958
Accession Number
95N26641
Funding Number(s)
CONTRACT_GRANT: NSF AST-90-17710
CONTRACT_GRANT: NAG2-402
Distribution Limits
Public
Copyright
Other
Document Inquiry

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