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Spitzer's Mid-Infrared View on an Outer-Galaxy Infrared Dark Cloud Candidate toward NGC 7538

Frieswijk, W. F. and Spaans, M. and Shipman, R. F. and Teyssier, D. and Carey, S. J. and Tielens, A. G. G. M. (2008) Spitzer's Mid-Infrared View on an Outer-Galaxy Infrared Dark Cloud Candidate toward NGC 7538. Astrophysical Journal Letters, 685 (1). L51-L54. ISSN 2041-8205.

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Infrared dark clouds (IRDCs) represent the earliest observed stages of clustered star formation, characterized by large column densities of cold and dense molecular material observed in silhouette against a bright background of mid-IR emission. Up to now, IRDCs were predominantly known toward the inner Galaxy where background infrared emission levels are high. We present Spitzer observations with the Infrared Array Camera toward object G111.80+0.58 (G111) in the outer Galactic plane, located at a distance of ~3 kpc from us and ~10 kpc from the Galactic center. Earlier results show that G111 is a massive, cold molecular clump very similar to IRDCs. The mid-IR Spitzer observations unambiguously detect object G111 in absorption. We have identified for the first time an IRDC in the outer Galaxy, which confirms the suggestion that cluster-forming clumps are present throughout the Galactic plane. However, against a low mid-IR background such as the outer Galaxy it takes some effort to find them.

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Carey, S. J.0000-0002-0221-6871
Additional Information:© 2008. The American Astronomical Society. Received 2008 February 7; accepted 2008 August 11; published 2008 September 20. Print publication: Issue 1 (2008 September 20). We thank the anonymous referee for his/her careful reading of the manuscript and his/her constructive remarks. Facilities: Spitzer (IRAC)
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:dust, extinction; infrared: ISM; ISM: clouds; stars: formation
Issue or Number:1
Record Number:CaltechAUTHORS:FRIapjl08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13013
Deposited By: Archive Administrator
Deposited On:15 Jan 2009 07:59
Last Modified:03 Oct 2019 00:33

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