SDSS 0809+1729: Connections Between Extremely Metal Poor Galaxies and   Gamma Ray Burst Hosts
  We discuss the serendipitous discovery of an extremely metal poor galaxy, SDSS 0809+1729, classified as a star in the Sloan Digital Sky Survey (SDSS). The galaxy has a redshift z = 0.0441 and a B-band absolute magnitude M_B = -17.1. With a metallicity of log(O/H)+12~7.44 or ~1/20 solar, this galaxy is among the 10 most metal poor emission-line galaxies known. SDSS 0809+1729 is a blue compact galaxy (BCG) with a stellar age of ~4.5 Myr, a star formation rate of 0.18 Msun/yr, and a large gas-phase electron density ~367/cm^3. Similar values of these parameters are common among other extremely metal poor galaxies, including IZw18. SDSS 0809+1729 is, however, unusual among BCGs because it lies in the same region of the luminosity-metallicity diagram as the two lowest metallicity long duration gamma ray burst (GRB) hosts. For a given B-band luminosity, both nearby GRB hosts and SDSS 0809+1729 have systematically lower metallicities than dwarf irregulars, the majority of BCGs, and normal star-forming galaxies. Because the star formation properties of SDSS 0809+1729 are similar to nearby long duration GRB hosts, SDSS 0809+1729 may be a potential GRB host. Identification of larger samples of similar extremely metal poor objects may provide important insights into the conditions required to produce long duration GRBs. 
Lisa J. Kewley (1), Warren R. Brown (2), Margaret J. Geller (2), Scott   J. Kenyon (2), Michael J. Kurtz (2) ((1) University...