A&A 558, A143 (2013) Astronomy DOI: 10.1051/0004-6361/201322276 & c ESO 2013 Astrophysics A metallicity study of 1987A-like supernova host galaxies, F. Taddia1, J. Sollerman1, A. Razza1, E. Gafton1,A.Pastorello2,C.Fransson1, M. D. Stritzinger3, G. Leloudas4,5, and M. Ergon1 1 The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, 10691 Stockholm, Sweden e-mail:
[email protected] 2 INAF – Osservatorio Astronomico di Padova, Vicolo dellOsservatorio 5, 35122 Padova, Italy 3 Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark 4 The Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova, 10691 Stockholm, Sweden 5 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark Received 14 July 2013 / Accepted 26 August 2013 ABSTRACT Context. The origin of the blue supergiant (BSG) progenitor of Supernova (SN) 1987A has long been debated, along with the role that its sub-solar metallicity played. We now have a sample of SN 1987A-like events that arise from the rare core collapse (CC) of massive (∼20 M) and compact (100 R)BSGs. Aims. The metallicity of the explosion sites of the known BSG SNe is investigated, as well as the association of BSG SNe to star- forming regions. Methods. Both indirect and direct metallicity measurements of 13 BSG SN host galaxies are presented, and compared to those of other CC SN types. Indirect measurements are based on the known luminosity-metallicity relation and on published metallicity gra- dients of spiral galaxies. In order to provide direct metallicity measurements based on strong line diagnostics, we obtained spectra of each BSG SN host galaxy both at the exact SN explosion sites and at the positions of other H ii regions.