High-Resolution IRAS Maps and Infrared Emission of M31. I. Morphology and Sources

January 1996 • 1996ApJ...456..152X

Authors • Xu, Cong • Helou, George

Abstract • The morphology of the infrared (IR) emission and the properties of discrete far-infrared (FIR) sources in the M31 disk are studied using the high-resolution (HiRes) maps from IRA S. Very thin and bright FIR arm segments are shown in these maps, which have similar structure as the H I gas but with much enhanced arm/ interarm contrast, typically a factor of ∼5 on the 60 microns image. We identify 39 unconfused sources (excluding the nucleus) and 14 confused sources (seven pairs) at 60 microns by direct Gaussian fittings to the image. IRAS colors of 10 bright isolated sources are studied, which are presumably representative of the discrete sources in general. The colors follow the well-known anticorrelation between ƒ_60μm/ƒ_100μm and ƒ_12μm/_ƒ25μm. All sources coincide with optical H II regions. A comparison with Hα observations shows that the total luminosity (in the wavelength range 8-1000 μm) associated with H II regions is 7.2±2.9 × 10⁸ L_sun, namely, 30%±14% of the total IR emission of M31. Half the IR luminosity of this component emerges from the sources. This luminosity translates into a present-day star formation rate of 0.36±0.14 M_sun yr^-1, about an order of magnitude lower than that of the Milky Way.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=1996ApJ...456..152X
• PREPRINT http://arxiv.org/abs/astro-ph/9507089
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/1996ApJ...456..152X
• GIF http://articles.adsabs.harvard.edu/full/1996ApJ...456..152X
• ARTICLE http://articles.adsabs.harvard.edu/full/1996ApJ...456..152X?defaultprint=YES
• SPIRES http://inspirehep.net/search?p=find+eprint+astro-ph/9507089