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Extinction map of the Small Magellanic Cloud based on SIRIUS and 6X 2MASS point source catalogs

Dobashi, Kazuhito and Bernard, Jean-Philippe and Kawamura, Akiko and Egusa, Fumi and Hughes, Annie and Paradis, Deborah and Bot, Caroline and Reach, William T. (2009) Extinction map of the Small Magellanic Cloud based on SIRIUS and 6X 2MASS point source catalogs. Astronomical Journal, 137 (6). pp. 5099-5109. ISSN 0004-6256.

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In this paper, we present the first extinction map of the Small Magellanic Cloud (SMC) constructed using the color excess at near-infrared wavelengths. Using a new technique named "X percentile method", which we developed recently to measure the color excess of dark clouds embedded within a star distribution, we have derived an E(J – H) map based on the SIRIUS and 6X Two Micron All Sky Survey (2MASS) star catalogs. Several dark clouds are detected in the map derived from the SIRIUS star catalog, which is deeper than the 6X 2MASS catalog. We have compared the E(J – H) map with a model calculation in order to infer the locations of the clouds along the line of sight, and found that many of them are likely to be located in or elongated toward the far side of the SMC. Most of the dark clouds found in the E(J – H) map have counterparts in the CO clouds detected by Mizuno et al. with the NANTEN telescope. A comparison of the E(J – H) map with the virial mass derived from the CO data indicates that the dust-to-gas ratio in the SMC varies in the range A_V /N_H = 1-2 × 10^(–22) mag H^-1 cm^2 with a mean value of ~1.5 × 10^(–22) mag H^-1 cm^2. If the virial mass underestimates the true cloud mass by a factor of ~2, as recently suggested by Bot et al., the mean value would decrease to ~8×10^(–23) mag H^-1 cm^2, in good agreement with the value reported by Gordon et al., 7.59 × 10^(–23) mag H^-1 cm^2.

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Reach, William T.0000-0001-8362-4094
Additional Information:© 2009 American Astronomical Society. Print publication: Issue 6 (2009 June) Received 2008 October 9; accepted for publication 2009 March 27; published 2009 May 12. We are grateful to D. Kato and R. Cutri for their useful advice regarding the SIRIUS and 6X 2MASS star catalogs. This work was financially supported by Ito Science Society (H19), as well as by Yamada Science Foundation for the promotion of the natural sciences (2008-1125). This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
Funding AgencyGrant Number
Ito Science SocietyH19
Yamada Science Foundation2008-1125
Subject Keywords:dust, extinction; ISM: clouds; Magellanic Clouds
Issue or Number:6
Record Number:CaltechAUTHORS:20090715-115656739
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14593
Deposited By: Jason Perez
Deposited On:11 Aug 2009 17:39
Last Modified:03 Oct 2019 00:51

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