0422−476: a shell galaxy with azimuthally distributed shells |
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| Authors: | A Wilkinson J-L Prieur R Lemoine D Carter D Malin W B Sparks |
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| Institution: | Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL;Observatoire de Toulouse, 14 Avenue Edward Belin, F‐31400 Toulouse, France;Vrije Universitieit Brussel, Astrofisisch Institut, Pleinlaan 2, B‐1050 Brussel, Belgium;John Moores University, Astrophysics Research Institute, 12 Quays House, Egerton Wharf, Birkenhead, Liverpool L41 1LD;Anglo-Australian Observatory, PO Box 297, 167 Vimiera Road, Epping, NSW 2121, Australia;Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21218, USA |
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| Abstract: | A morphological and two-colour charge-coupled device photometry study of the shell galaxy 0422−476, one of the richest known azimuthally distributed shell galaxies, is presented. Taking this galaxy as a prototype, a general method for reducing observational data of these objects is defined and quantitative parameters for use in further theoretical studies are derived.
According to some recent models (e.g. that of Thomson and Wright in 1990), the shells in such a galaxy could be density waves induced in a thick disc population of dynamically cold stars by a weak interaction with another galaxy. In 0422−476 there is no evidence of either a conventional exponential disc or a thick disc. Although it is not possible to rule out the weak interaction model, the observations continue to favour the merger model (e.g. that of Quinn from 1984). |
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| Keywords: | galaxies: evolution galaxies: individual: 0422−476 galaxies: interactions galaxies: photometry |
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