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The ACS Nearby Galaxy Survey Treasury. I. The Star Formation History of the M81 Outer Disk


Williams, BF and Dalcanton, JJ and Seth, AC and Weisz, D and Dolphin, A and Skillman, E and Harris, J and Holtzman, J and Girardi, L and de Jong, RS and Olsen, K and Cole, AA and Gallart, C and Gogarten, SM and Hidalgo, SL and Mateo, M and Rosema, K and Stetson, PB and Quinn, T, The ACS Nearby Galaxy Survey Treasury. I. The Star Formation History of the M81 Outer Disk, The Astronomical Journal, 137, (1) pp. 419-430. ISSN 0004-6256 (2009) [Refereed Article]

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Copyright 2009 The American Astronomical Society

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DOI: doi:10.1088/0004-6256/137/1/419


The Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury is a large Hubble Space Telescope (HST)/ACS treasury program to obtain resolved stellar photometry for a volume-limited sample of galaxies out to 4 Mpc. As part of this program, we have obtained deep ACS imaging of a field in the outer disk of the large spiral galaxy M81. The field contains the outskirts of a spiral arm as well as an area containing no current star formation. Our imaging results in a color-magnitude diagram (CMD) reaching to m F814W = 28.8 and m F606W = 29.5, one magnitude fainter than the red clump. Through detailed modeling of the full CMD, we quantify the age and metallicity distribution of the stellar populations contained in the field. The mean metallicity in the field is 1 < [M/H] < 0 and only a small fraction of stars have ages 1 Gyr. The results show that most of the stars in this outer disk field were formed by z ~ 1 and that the arm structure at this radius has a lifetime of 100 Myr. We discuss the measured evolution of the M81 disk in the context of surveys of high redshift disk galaxies and deep stellar photometry of other nearby galaxies. All of these indicate that massive spiral disks are mostly formed by z ~ 1 and that they have experienced rapid metal enrichment.

Item Details

Item Type:Refereed Article
Keywords:galaxies: individual (M81); galaxies: stellar content; galaxies: spiral; galaxies: evolution
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cole, AA (Professor Andrew Cole)
ID Code:56319
Year Published:2009
Web of Science® Times Cited:52
Deposited By:Physics
Deposited On:2009-04-21
Last Modified:2010-03-25
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