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Internal extinction of disc galaxies – I. High-resolution extinction map of NGC 6946

Trewhella, M. (1998) Internal extinction of disc galaxies – I. High-resolution extinction map of NGC 6946. Monthly Notices of the Royal Astronomical Society, 297 (3). pp. 807-816. ISSN 0035-8711.

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Traditionally, it has been believed that extinction effects due to dust within the interstellar medium of external galaxies are rather small and can largely be ignored. Over the last 10 years, however, considerable doubt has been cast over the evidence to support this comfortable idea, and it has become clear that a more detailed analysis is required. Here, a new technique for mapping the extinction in disc galaxies with high resolution is presented. This technique has been applied to the Sc galaxy NGC 6946. The results show that dust extinction significantly affects both the overall brightness and appearance of the galaxy. The total extinction is found to be A_B=0.45 – somewhat larger than the value of A_B=0.2 usually quoted for an Sc galaxy. When corrected for dust the morphology more closely resembles that of an Sb galaxy rather than an Sc galaxy. The most surprising result of this work is finding interarm regions that suffer high extinction. It appears that these regions appear faint because of the high extinction and not as a result of low stellar density. There are also interarm regions that suffer little extinction; these are therefore truly regions of low stellar density.

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Additional Information:© 1998 Royal Astronomical Society. Accepted 1998 February 11. Received 1998 February 11; in original form 1997 September 29. I acknowledge and appreciate the support of a PPARC PhD studentship at the University of Wales Cardiff, where this research was carried out. For the observations, I thank the time allocation committees of ISO, WIRO and KPNO, the IPAC staff, and Harley Thronson and Nick Devereux for their efforts. The paper benefited greatly from discussions with Jon Davies, Paul Alton, Simone Bianchi, Nick Kylafis, Manolis Xilouris, John Beckman and Barry Madore. I acknowledge the support of a Jet Propulsion Laboratory post-doctoral fellowship whilst writing this paper.
Group:Infrared Processing and Analysis Center (IPAC)
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Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Subject Keywords:dust, extinction, galaxies: individual: NGC 6946, galaxies: ISM, galaxies: spiral
Issue or Number:3
Record Number:CaltechAUTHORS:20170408-212554145
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Official Citation:M. Trewhella; Internal extinction of disc galaxies – I. High-resolution extinction map of NGC 6946, Monthly Notices of the Royal Astronomical Society, Volume 297, Issue 3, 1 July 1998, Pages 807–816,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76404
Deposited By: 1Science Import
Deposited On:26 Mar 2018 22:43
Last Modified:03 Oct 2019 17:00

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