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Dust in the eye of Andromeda

Marsh, K A ORCID: https://orcid.org/0000-0003-0107-7803, Whitworth, A P ORCID: https://orcid.org/0000-0002-1178-5486, Smith, M W L ORCID: https://orcid.org/0000-0002-3532-6970, Lomax, O ORCID: https://orcid.org/0000-0002-1641-4318 and Eales, S A ORCID: https://orcid.org/0000-0002-7394-426X 2018. Dust in the eye of Andromeda. Monthly Notices of the Royal Astronomical Society 480 (3) , pp. 3052-3061. 10.1093/mnras/sty2037

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Abstract

We present new Herschel-derived images of warm dust in the Andromeda galaxy, M31, with unprecedented spatial resolution (∼30 pc), column density accuracy, and constraints on the three-dimensional distributions of dust temperature and dust opacity index (hence grain size and composition), based on the new ppmap Bayesian analysis procedure. We confirm the overall radial variation of dust opacity index reported by other recent studies, including the central decrease within ∼3 kpc of the nucleus. We also investigate the detailed distribution of dust in the nuclear region, a prominent feature of which is an ∼500 pc bar-like structure seen previously in H α. The nature of this feature has been the subject of some debate. Our maps show it to be the site of the warmest dust, with a mean line-of-sight temperature ∼30 K. A comparison with the stellar distribution, based on 2MASS data, provides strong evidence that it is a gravitationally induced bar. A comparison with radial velocity maps suggests the presence of an inflow towards the nucleus from opposite directions along this bar, fed presumably by the nuclear spiral with which it appears to connect. Such behaviour is common in large-scale bars in spiral galaxies, as is the phenomenon of nested bars whereby a subkiloparsec nuclear bar exists within a large-scale primary bar. We suggest that M31 represents an example of such nesting.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Advanced Research Computing @ Cardiff (ARCCA)
Publisher: Oxford University Press
ISSN: 0035-8711
Date of First Compliant Deposit: 9 November 2018
Date of Acceptance: 26 July 2018
Last Modified: 03 May 2023 12:07
URI: https://orca.cardiff.ac.uk/id/eprint/116621

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