Journal Article

Star formation in H <span class="smallCaps">i</span> tails: HCG 92, HCG 100 and six interacting systems

D. F. de Mello, F. Urrutia-Viscarra, C. Mendes de Oliveira, S. Torres-Flores, E. R. Carrasco and E. Cypriano

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 426, issue 3, pages 2441-2451
Published in print November 2012 | ISSN: 0035-8711
Published online November 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21429.x
Star formation in H i tails: HCG 92, HCG 100 and six interacting systems

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We present new Gemini spectra of 14 new objects found within the H i tails of Hickson Compact Groups (HCGs) 92 and 100. Nine of them are Galaxy Evolution Explorer (GALEX) far-ultraviolet (FUV) and near-ultraviolet (NUV) sources. The spectra confirm that these objects are members of the compact groups and have metallicities close to solar, with an average value of 12+log(O/H) ∼ 8.5. They have average FUV luminosities 7 × 1040 erg s−1 and very young ages (<100 Myr), and two of them resemble tidal dwarf galaxy (TDG) candidates. We suggest that they were created within gas clouds that were ejected during galaxy–galaxy interactions into the intergalactic medium, which would explain the high metallicities of the objects, inherited from the parent galaxies from which the gas originated. We conduct a search for similar objects in six interacting systems with extended H i tails: NGC 2623, NGC 3079, NGC 3359, NGC 3627, NGC 3718 and NGC 4656. We found 35 ultraviolet (UV) sources with ages < 100 Myr; however, most of them are on average less luminous/massive than the UV sources found around HCG 92 and HCG 100. We speculate that this might be an environmental effect and that compact groups of galaxies are more favourable to TDG formation than other interacting systems.

Keywords: galaxies: interactions; intergalactic medium; galaxies: star clusters: general; galaxies: star formation

Journal Article.  6288 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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