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Radial variations of the SFHs of dwarf irregular galaxies†

Published online by Cambridge University Press:  17 August 2012

Hong-Xin Zhang ,
Deidre A. Hunter ,
Bruce G. Elmegreen ,
Yu Gao  and
Andreas Schruba
Hong-Xin Zhang
Affiliation:
Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, Arizona 86001USA email: hxzhang@lowell.edu; dah@lowell.edu Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008China Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008China Graduate School of the Chinese Academy of Sciences, Beijing 100080China
Deidre A. Hunter
Affiliation:
Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, Arizona 86001USA email: hxzhang@lowell.edu; dah@lowell.edu
Bruce G. Elmegreen
Affiliation:
IBM T. J. Watson Research Center, PO Box 218, Yorktown Heights, New York 10598USA
Yu Gao
Affiliation:
Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008China Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008China
Andreas Schruba
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 HeidelbergGermany
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Abstract

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The LITTLE THINGS project† has compiled multi-wavelength data (including VLA hi-line emission maps, GALEX FUV/NUV imagery, UBV, narrow-band Hα, and Spitzer images) for a representative sample of nearby dwarf irregular (dIrr) galaxies. The broadband data are used to constrain the radial variations of the star formation (SF) rate (SFR) averaged over the past 0.1 Gyr, 1 Gyr and a Hubble time, with a complete library of model SF histories (SFHs). The recent SF of more than ~ 80% of the dIrrs in our sample has been concentrated in the inner disk, and the SF in the outer disk has been markedly suppressed. This outside-in shrinking of the star-forming disk leaves a down-bending (double exponential) stellar mass surface density (Σ*) distribution. Our findings in dIrrs are in contrast to the inside-out disk growth scenario suggested for luminous spiral galaxies.

Keywords

galaxies: dwarf – galaxies: irregular – galaxies: evolution – galaxies: stellar content
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 7 , Symposium S284: The Spectral Energy Distribution of Galaxies , September 2011 , pp. 345 - 348
Copyright
Copyright © International Astronomical Union 2012

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