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Far-ultraviolet observations of the Ophiuchus region with SPEAR

Lee, D.-H. and Seon, K.-I. and Min, K. W. and Park, Y. S. and Yuk, I. S. and Edelstein, J. and Korpela, E. J. and Sankrit, R. and Park, S. J. and Ryu, K. S. (2008) Far-ultraviolet observations of the Ophiuchus region with SPEAR. Astrophysical Journal, 686 (2). pp. 1155-1161. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:LEEapj08

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Abstract

We present the first far-ultraviolet (FUV; 1370-1670 Å) image of the Ophiuchus molecular cloud region, observed with the SPEAR imaging spectrograph. The flux levels of the diffuse FUV continuum are in reasonable agreement with those of the Voyager observations in the shorter FUV wavelengths (912-1216 Å), provided that the diffuse FUV emission is dominated by the spectra from late O- and early B-type stars. The observed region of the present study was divided into five subregions according to their FUV intensities, and the spectrum was obtained for each subregion with prominent H_2 fluorescent emission lines. A synthetic model of the H_2 fluorescent emission indicates that the molecular cloud has more or less uniform physical parameters over the Ophiuchus region, with a hydrogen density n_H of 500 cm^−3 and a H2 column density N(H_2) of 2 × 10^(20) cm^−2. It is notable that the observed diffuse FUV continuum is well reproduced by a single-scattering model with scattered starlight from the dust cloud located at ~120-130 pc, except at a couple of regions with high optical depth. The model also gives reasonable properties of the dust grains of the cloud with an albedo a of 0.36 ± 0.20 and a phase function asymmetry factor g of 0.52 ± 0.22.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1086/591778DOIUNSPECIFIED
http://www.iop.org/EJ/abstract/0004-637X/686/2/1155/PublisherUNSPECIFIED
Additional Information:© 2008 The American Astronomical Society. Received 2007 July 1, accepted for publication 2008 July 2. The authors would like to thank the anonymous referee for the useful comments which helped to clarify and significantly improve the paper. This publication makes use of data products from SPEAR/FIMS, which is a joint project of the Korea Astronomy and Space Science Institute, the Korea Advanced Institute of Science and Technology, and the University of California at Berkeley, funded by the Ministry of Science and Technology (Korea) and by a grant from NASA.
Funders:
Funding AgencyGrant Number
Ministry of Science and Technology (Korea)UNSPECIFIED
NASAUNSPECIFIED
Subject Keywords:ISM: individual (Ophiuchus); ISM: lines and bands; ultraviolet: ISM
Issue or Number:2
Record Number:CaltechAUTHORS:LEEapj08
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:LEEapj08
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13589
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 May 2009 20:46
Last Modified:27 Mar 2014 05:48

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