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Star Formation in NGC 5194 (M51a). II. The Spatially Resolved Star Formation Law

Kennicutt, Robert C., Jr. and Calzetti, Daniela and Walter, Fabian and Helou, George and Hollenbach, David J. and Armus, Lee and Bendo, George and Dale, Daniel A. and Draine, Bruce T. and Engelbracht, Charles W. and Gordon, Karl D. and Prescott, Moire K. M. and Regan, Michael W. and Thornley, Michele D. and Bot, Caroline and Brinks, Elias and de Blok, Erwin and de Mello, Dulia and Meyer, Martin and Moustakas, John and Murphy, Eric J. and Sheth, Kartik and Smith, J. D. T. (2007) Star Formation in NGC 5194 (M51a). II. The Spatially Resolved Star Formation Law. Astrophysical Journal, 671 (1). pp. 333-348. ISSN 0004-637X.

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We have studied the relationship between the star formation rate (SFR), surface density, and gas surface density in the spiral galaxy M51a (NGC 5194), using multiwavelength data obtained as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS). We introduce a new SFR index based on a linear combination of Hα emission-line and 24 μm continuum luminosities, which provides reliable extinction-corrected ionizing fluxes and SFR densities over a wide range of dust attenuations. The combination of these extinction-corrected SFR densities with aperture synthesis H I and CO maps has allowed us to probe the form of the spatially resolved star formation law on scales of 0.5-2 kpc. We find that the resolved SFR versus gas surface density relation is well represented by a Schmidt power law, which is similar in form and dispersion to the disk-averaged Schmidt law. We observe a comparably strong correlation of the SFR surface density with the molecular gas surface density, but no significant correlation with the surface density of atomic gas. The best-fitting slope of the Schmidt law varies from N = 1.37 to 1.56, with zero point and slope that change systematically with the spatial sampling scale. We tentatively attribute these variations to the effects of areal sampling and averaging of a nonlinear intrinsic star formation law. Our data can also be fitted by an alternative parameterization of the SFR surface density in terms of the ratio of gas surface density to local dynamical time, but with a considerable dispersion.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Kennicutt, Robert C., Jr.0000-0001-5448-1821
Calzetti, Daniela0000-0002-5189-8004
Walter, Fabian0000-0003-4793-7880
Helou, George0000-0003-3367-3415
Armus, Lee0000-0003-3498-2973
Dale, Daniel A.0000-0002-5782-9093
Draine, Bruce T.0000-0002-0846-936X
Brinks, Elias0000-0002-7758-9699
Murphy, Eric J.0000-0001-7089-7325
Sheth, Kartik0000-0002-5496-4118
Smith, J. D. T.0000-0003-1545-5078
Additional Information:© 2007 The American Astronomical Society. Received 2007 April 29; accepted 2007 August 7. We would like to acknowledge valuable discussions with a number of colleagues, including Ayesha Begum, Hsiao-WenChen, Cathie Clarke, Crystal Martin, Phil Solomon, and Art Wolfe. We thank the anonymous referee for a careful reading of the manuscript. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:galaxies : evolution; galaxies : individual (M51a, NGC 5194); galaxies : ISM; HII regions; infrared : galaxies; stars : formation
Issue or Number:1
Record Number:CaltechAUTHORS:20100222-113208974
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Official Citation:Star Formation in NGC 5194 (M51a). II. The Spatially Resolved Star Formation Law Robert C. Kennicutt, Jr., Daniela Calzetti, Fabian Walter, George Helou, David J. Hollenbach, Lee Armus, George Bendo, Daniel A. Dale, Bruce T. Draine, Charles W. Engelbracht, Karl D. Gordon, Moire K. M. Prescott, Michael W. Regan, Michele D. Thornley, Caroline Bot, Elias Brinks, Erwin de Blok, Dulia de Mello, Martin Meyer, John Moustakas, Eric J. Murphy, Kartik Sheth, and J. D. T. Smith 2007 ApJ 671 333-348 doi: 10.1086/522300
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17553
Deposited By: Tony Diaz
Deposited On:02 Mar 2010 17:24
Last Modified:09 Mar 2020 13:18

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