Infrared Array Camera (IRAC) observations of M81

S. P. Willner, M. L.N. Ashby, P. Barmby, G. G. Fazio, M. Pahre, H. A. Smith, Robert C. Kennicutt, Daniela Calzetti, Daniel A. Dale, B. T. Draine, Michael W. Regan, S. Malhotra, Michele D. Thornley, P. N. Appleton, D. Frayer, G. Helou, S. Stolovy, L. Storrie-Lombardi

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Infrared Array Camera (IRAC) images of M81 show three distinct morphological constituents: a smooth distribution of evolved stars with bulge, disk, and spiral arm components; a clumpy distribution of dust emission tracing the spiral arms; and a pointlike nuclear source. The bulge stellar colors are consistent with M-type giants, and the disk colors are consistent with a slightly younger population. The dust emission generally follows the blue and ultraviolet emission, but there are large areas that have dust emission without ultraviolet and smaller areas with ultraviolet but little dust emission. The former are presumably caused by extinction, and the latter may be due to cavities in the gas and dust created by supernova explosions. The nucleus appears fainter at 8 μm than expected from ground-based 10 μm observations made 4 years ago.

Original languageEnglish (US)
Pages (from-to)222-228
Number of pages7
JournalAstrophysical Journal, Supplement Series
Volume154
Issue number1
DOIs
StatePublished - Sep 2004

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Dust, extinction
  • Galaxies: ISM
  • Galaxies: Individual (M81)
  • Galaxies: Spiral
  • Galaxies: Stellar content
  • Infrared: Galaxies

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