Journal Article

On the scarcity of Magellanic Cloud like satellites

Phil A. James and Clare F. Ivory

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 411, issue 1, pages 495-504
Published in print February 2011 | ISSN: 0035-8711
Published online January 2011 | e-ISSN: 1365-2966 | DOI:
On the scarcity of Magellanic Cloud like satellites

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We have used Hα narrow-band imaging to search for star-forming satellite galaxies around 143 luminous spiral galaxies, with the goal of quantifying the frequency of occurrence of satellites resembling the Magellanic Clouds, around galaxies comparable to the Milky Way. For two-thirds of the central galaxies, no star-forming satellites are found, down to luminosities and star formation rates well below those of the Magellanic Clouds. A total of 62 satellites are found, associated with 47 of the central galaxies searched. The R-band magnitude difference between central galaxies and their satellites has a median value of 4.6 mag and a maximum value of 10.2 mag. The mean projected separation of the satellites from their central galaxies is 81 kpc, or 98 kpc for systems beyond 30 Mpc. Thus, star-forming satellites are quite rare, and the Milky Way is unusual both for the luminosity and the proximity of its two brightest satellites. We also find that the Clouds themselves are unusual in that they appear to form a bound binary pair; such close satellite pairs, of any luminosity, are also extremely rare in our survey.

Keywords: galaxies: groups: general; Magellanic Clouds; galaxies: spiral

Journal Article.  7912 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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