2004/05/31 by S. P. Willner, M. L. N. Ashby, P. Barmby +24 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Bulge #Dust lane #Extinction (optical mineralogy) #Gamma-ray bursts and supernovae #Infrared #Optics #Physics #Population #Spiral galaxy #Star formation #Stars #Stellar population #Stellar, planetary, and galactic studies #Supernova #Ultraviolet #astro-ph
paper · pdf · doi:10.1086/422913
published as Astrophys.J.Suppl.154:222,2004 · ApJS in press (Spitzer special issue); 15 pages, 3 figures. Changes: unused references removed, numbers and labels in Table 1 changed
arxiv created 2004/06/21 · openalex publication_date 2004/09/01 · arxiv updated 2012/08/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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.