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Powerful H2 emission and star formation on the interacting galaxy system Arp 143: observations with Spitzer and Galex

Beirão, P. and Appleton, P. N. and Brandl, B. R. and Seibert, M. and Jarrett, T. and Houck, J. R. (2009) Powerful H2 emission and star formation on the interacting galaxy system Arp 143: observations with Spitzer and Galex. Astrophysical Journal, 693 (2). pp. 1650-1665. ISSN 0004-637X. doi:10.1088/0004-637X/693/2/1650.

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We present new mid-infrared (IR; 5–35 μm) and ultraviolet (1539–2316 Å) observations of the interacting galaxy system Arp 143 (NGC 2444/2445) from the Spitzer Space Telescope and Galaxy Evolution Explorer. In this system, the central nucleus of NGC 2445 is surrounded by knots of massive star formation in a ringlike structure. We find unusually strong emission from warm H2 associated with an expanding shock wave between the nucleus and the western knots. At this ridge, the flux ratio between H2 and polycyclic aromatic hydrocarbon (PAH) emission is nearly ten times higher than in the nucleus. Arp 143 is one of the most extreme cases known in that regard. From our multiwavelength data, we derive a narrow age range of the star forming knots between 2 Myr and 7.5 Myr, suggesting that the ring of knots was formed almost simultaneously in response to the shock wave traced by the H2 emission. However, the knots can be further subdivided into two age groups: those with an age of 2–4 Myr (knots A, C, E, and F), which are associated with 8μm emission from PAHs, and those with an age of 7–8 Myr (knots D and G), which show little or no 8μm emission shells surrounding them. We attribute this finding to an aging effect of the massive clusters which, after about 6 Myr, no longer excite the PAHs surrounding the knots.

Item Type:Article
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URLURL TypeDescription
Appleton, P. N.0000-0002-7607-8766
Seibert, M.0000-0002-1143-5515
Jarrett, T.0000-0002-4939-734X
Additional Information:©2009 The American Astronomical Society. Received 2008 October 17; accepted 2008 December 8; published 2009 March 10. We thank Y. Mayya for providing the Hα image. We also thank B. Groves and L. Snijders for making the Starburst99 and Mappings models available. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407.
Funding AgencyGrant Number
Subject Keywords:galaxies: individual (NGC 2444, NGC 2445); galaxies: interactions; galaxies: ISM; galaxies: starburst; infrared: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20090422-142843426
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14047
Deposited By: Marie Noren
Deposited On:29 Apr 2009 15:17
Last Modified:08 Nov 2021 22:42

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