The central regions of M81

Citation
Tj. Davidge et S. Courteau, The central regions of M81, ASTRONOM J, 117(6), 1999, pp. 2781-2788
Citations number
41
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMICAL JOURNAL
ISSN journal
00046256 → ACNP
Volume
117
Issue
6
Year of publication
1999
Pages
2781 - 2788
Database
ISI
SICI code
0004-6256(199906)117:6<2781:TCROM>2.0.ZU;2-L
Abstract
High-angular resolution near-infrared images obtained with the Canada-Franc e-Hawaii Telescope adaptive optics system are combined with archival Hubble Space Telescope data to investigate the central regions of the nearby Sb g alaxy M81 (NGC 3031). The spectral-energy distribution of the circumnuclear region, which extends out to 1." 5 (similar to 24 pc if mu(0) = 27.5) from the nucleus, can be modeled as a combination of an old metal-rich populati on and emission from hot dust. Thermal emission, which has been attributed to hot dust, has been detected near other active galactic nuclei, and simpl e models indicate that hot dust can account for similar to 20% of the light in K within 0." 5 of the M81 nucleus. An elongated structure with M-V simi lar to -7, which may be an area of active star formation, is detected 0." 4 5 from the nucleus. At distances in excess of 1." 5 from the nucleus, the J -K color of the M81 bulge is not significantly different from what is seen in M31. The HST data are also used to search for bright globular clusters w ithin 2 kpc of the center of M81. The area within 0.26 kpc of the M81 nucle us is largely devoid of bright globular clusters, in agreement with what is seen in the central regions of the Galaxy and M31. However, our survey ind icates that there may be similar to 45 +/- 12 globular cluster candidates w ith M-V less than or equal to -7 within 2 kpc of the galaxy center, which i s consistent with what would be infrared from the Milky Way cluster system after adjusting for differences in the total number of clusters.