John M. Cannon et al 2005 ApJ 630 L37 doi:10.1086/491671
John M. Cannon1, Fabian Walter1, George J. Bendo2, Daniela Calzetti3, Daniel A. Dale4, Bruce T. Draine5, Charles W. Engelbracht2, Karl D. Gordon2, George Helou6, Robert C. Kennicutt, Jr.2, Eric J. Murphy7, Michele D. Thornley8, Lee Armus6, David J. Hollenbach9, Claus Leitherer3, Michael W. Regan3, Hélène Roussel6 and Kartik Sheth6
Show affiliationsWe present spatially resolved Spitzer Space Telescope imaging of the supergiant shell region of the M81 group dwarf galaxy IC 2574 obtained as part of the Spitzer Infrared Nearby Galaxies Survey. This region harbors one of the best nearby examples of a kinematically distinct H I shell, with an associated remnant stellar cluster; the shell is initiating sequential star formation as it interacts with the surrounding interstellar medium. This region dominates the infrared luminosity of IC 2574 and is spatially resolved in all Spitzer imaging bands. We study the differences in dust temperature as a function of local environment and compare local star formation rates as inferred from Hα and total infrared luminosities. We find that the strong Hα sources are associated with regions of warm dust; however, the most luminous infrared and Hα sources are not necessarily cospatial. The coolest dust is found in the regions farthest from the rim of the shell; these regions show the best agreement between star formation rates derived from Hα and from total infrared luminosities (although discrepancies at the factor of 3-4 level still exist). There is considerable variation in the radio-far-infrared correlation in different regions surrounding the shell. The low dust content of the region may influence the scatter seen in these relations; these data demonstrate that the expanding shell is dramatically affecting its surroundings by triggering star formation and altering the dust temperature.
galaxies: dwarf; galaxies: individual (IC 2574); galaxies: irregular; galaxies: ISM; infrared: galaxies
Issue 1 (2005 September 1)
Received 2005 June 23, accepted for publication 2005 July 28
Published 2005 August 16
John M. Cannon et al 2005 ApJ 630 L37
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