Infrared Array Camera (IRAC) Observations of M81 (original) (raw)

NASA/ADS

;

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

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.

Publication:

The Astrophysical Journal Supplement Series

Pub Date:

September 2004

DOI:

10.1086/422913

arXiv:

arXiv:astro-ph/0405626

Bibcode:

2004ApJS..154..222W

Keywords:

• ISM: Dust;
• Extinction;
• Galaxies: Individual: Messier Number: M81;
• Galaxies: ISM;
• Galaxies: Spiral;
• Galaxies: Stellar Content;
• Infrared: Galaxies;
• Astrophysics

E-Print:

ApJS in press (Spitzer special issue)