Tabatabaei, F. S., Braine, J., Xilouris, E. M., Kramer, C., Boquien, M., Combes, E., Henkel, C., Relano, M., Verley, S., Gratier, P., Israel, F., Wiedner, M. C., Roellig, M., Schuster, K. F. and van der Werf, P. (2014). Variation in the dust emissivity index across M33 with Herschel and Spitzer (HerM 33es). Astron. Astrophys., 561. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746
Full text not available from this repository.Abstract
We study the wavelength dependence of the dust emission as a function of position and environment across the disk of M33 using Spitzer and Herschel photometric data. M33 is a Local Group spiral with slightly subsolar metallicity, which makes it an ideal stepping-stone to less regular and lower-metallicity objects such as dwarf galaxies and, probably, young-universe objects. Expressing the emissivity of the dust as a power law, the power-law exponent (beta) was estimated from two independent approaches designed to properly treat the degeneracy between beta and the dust temperature (T). Both beta and T are higher in the inner than in the outer disk, contrary to reported beta - T anti-correlations found in other sources. In the cold + warm dust model, the warm component and the ionized gas (H alpha) have a very similar distribution across the galaxy, demonstrating that the model separates the components in an appropriate way. Both cold-and warm-dust column densities are high in star-forming regions and reach their maxima toward the giant star-forming complexes NGC 604 and NGC595. beta declines from close to 2 in the center to about 1.3 in the outer disk. beta is positively correlated with star formation and with the molecular gas column, as traced by the H alpha and CO emission. The lower dust-emissivity index in the outer parts of M33 is most likely related to the reduced metallicity (different grain composition) and possibly to a different size distribution. It is not due to the decrease in stellar radiation field or temperature in a simple way because the far-infrared-bright regions in the outer disk also have a low beta. Like most spirals, M33 has a (decreasing) radial gradient in star formation and molecular-to-atomic gas ratio such that the regions bright in H alpha or CO tend to trace the inner disk, which makes it difficult to distinguish between their effects on the dust. The assumption of a constant emissivity index beta is obviously not appropriate.
| Item Type: | Journal Article | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| URN: | urn:nbn:de:hbz:38-451744 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| DOI: | 10.1051/0004-6361/201321441 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Journal or Publication Title: | Astron. Astrophys. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Volume: | 561 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Date: | 2014 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Publisher: | EDP SCIENCES S A | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Place of Publication: | LES ULIS CEDEX A | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ISSN: | 1432-0746 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Language: | English | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Faculty: | Unspecified | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Divisions: | Unspecified | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Subjects: | no entry | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| URI: | http://kups.ub.uni-koeln.de/id/eprint/45174 |
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