Early-type host galaxies of Type II and Ib Supernovae
  Recent studies find that some early-type galaxies host Type II or Ibc
supernovae (SNe II, Ibc). This may imply recent star-formation activities in
these SNe host galaxies, but a massive star origin of the SNe Ib so far
observed in early-type galaxies has been questioned because of their intrinsic
faintness and unusually strong Ca lines shown in the nebular phase. To address
the issue, we investigate the properties of early-type SNe host galaxies using
the data with Galaxy Evolution Explore(GALEX) ultraviolet photometry, and the
Sloan Digital Sky Survey (SDSS) optical data. Our sample includes eight SNe II
and one peculiar SN Ib (SN 2000ds) host galaxies as well as 32 SN Ia host
galaxies. The host galaxy of SN 2005cz, another peculiar SN Ib, is also
analysed using the GALEX data and the NASA/IPAC Extragalactic Database (NED)
optical data. We find that the NUV-optical colors of SN II/Ib host galaxies are
systematically bluer than those of SN Ia host galaxies, and some SN II/Ib host
galaxies with NUV-r colors markedly bluer than the others exhibit strong radio
emission. We perform a stellar population synthesis analysis and find a clear
signature of recent star-formation activities in most of the SN II/Ib host
galaxies. Our results generally support the association of the SNe II/Ib hosted
in early-type galaxies with core-collapse of massive stars. We briefly discuss
implications for the progenitors of the peculiar SNe Ib 2000ds and 2005cz.
