Chemical abundances of seven irregular and three tidal dwarf galaxies in the M81 group

Kevin V. Croxall, Liese Van Zee, Henry Lee, Evan D. Skillman, Janice C. Lee, Stéphanie Cté, Robert C. Kennicutt, Bryan W. Miller

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

We have derived nebular abundances for 10 dwarf galaxies belonging to the M81 Group, including several galaxies which do not have abundances previously reported in the literature. For each galaxy, multiple H II regions were observed with GMOS-N at the Gemini Observatory in order to determine abundances of several elements (oxygen, nitrogen, sulfur, neon, and argon). For seven galaxies, at least one H II region had a detection of the temperature sensitive [O III] λ4363 line, allowing a "direct" determination of the oxygen abundance. No abundance gradients were detected in the targeted galaxies, and the observed oxygen abundances are typically in agreement with the well-known metallicity-luminosity relation. However, three candidate "tidal dwarf" galaxies lie well off this relation: UGC 5336, Garland, and KDG 61. The nature of these systems suggests that UGC 5336 and Garland are indeed recently formed systems, whereas KDG 61 is most likely a dwarf spheroidal galaxy which lies along the same line of sight as the M81 tidal debris field. We propose that these H II regions formed from previously enriched gas which was stripped from nearby massive galaxies (e.g., NGC 3077 and M81) during a recent tidal interaction.

Original languageEnglish (US)
Pages (from-to)723-738
Number of pages16
JournalAstrophysical Journal
Volume705
Issue number1
DOIs
StatePublished - 2009

Keywords

  • Galaxies: Abundances
  • Galaxies: Dwarf
  • Galaxies: Individual (Garland, KDG 61, UGC 5336)
  • Galaxies: Interactions

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