Supernova 2007bi

Abstract

R. Chornock, A. V. Filippenko, R. J. Foley, D. A. Perley, J. M. Silverman, J. S. Bloom, D. Kocevski, and W. Li, University of California, Berkeley, report that CCD spectra (range 310-920 nm) of 2007bi were obtained on Apr. 15.6 and 16.4 UT with LRIS on the Keck I 10-m telescope under poor conditions. They identify weak narrow emission features near 420.1 and 739.7 nm with [O II] 372.7-nm and H-alpha (respectively) nebular emission lines from the host galaxy at a redshift of 0.127. After removal of this redshift, the object bears a striking resemblance to the peculiar type-Ic supernova 1999as (Knop et al. 1999, IAUC 7128; Hatano et al. 2001, Bull. AAS 198, 3902) at 25 days past discovery, with an additional strong emission feature near 731 nm (FWHM about 6000 km/s). Absorption features identified as Ca II H and K, as well as Fe II (492.4, 501.8, and 516.9 nm), are present – blueshifted by 12000 km/s. The Fe II absorptions are unusually narrow (FWHM about 3000 km/s). Assuming a distance modulus at this redshift of 38.8, the supernova is quite luminous (absolute magnitude -20.5). A faint galaxy, presumably the host, is present in the Sloan Digital Sky Survey (Adelman- McCarthy et al. 2006, Ap.J. Suppl. 162, 38) within 1 arcsec of the position of the supernova, with an absolute g magnitude of M_g = -16.4. The relatively narrow Fe II absorptions, high luminosity of the supernova, and faint host luminosity are all similar to that of SN 1999as.

Publication
Central Bureau Electronic Telegrams