The stellar populations of metalrich starburst galaxies the frequency of Wolf Rayet stars

Joao Rodrigo Souza Leao,1 Claus Leitherer,1 Fabio Bresolin2 & Roberto Cid Fernandes3

1Space Telescope Science Institute, Baltimore, MD, USA 2IfA, University ofHawai'i, Honolulu, HI, USA 3 Universidade Federal de Santa Catarina, Florianopolis, SC, Brazil

We conducted an optical survey (Keck Telescope, 3,700-7,000 A) of 24 high-metallicity (Z) starburst galaxies to investigate whether high-Z environments favor the formation of Wolf-Rayet (WR) stars. We searched for the presence of the He ii 4686 A line produced by the massive WR stars. We detected this feature in six galaxies (25% of the sample). We also used a stellar-population-synthesis code to determine their ages. We find that (i) all galaxies hosting considerable numbers of WR stars are very young systems, with ages log(t) < 8, with t in years; (ii) not all young star-forming galaxies host WR stars, or at least that population cannot be detected in their integrated spectra; and (iii) most galaxies hosting WR populations are found in interacting systems. We for the first time detect WR populations in galaxies ESO 485-G003, NGC 6090, and NGC 2798.

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