Supernova 2007gi in NGC 4036
Abstract
A. Harutyunyan, S. Benetti, E. Cappellaro, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova; F. Patat, European Southern Observatory; and F. Ghinassi, Telescopio Nazionale Galileo (TNG), report that a spectrum of 2007gi (cf. CBET 1017), obtained on Aug. 4.90 UT with the 3.5-m TNG (+ DOLORES; range 380-750 nm, resolution 1.8 nm), shows it to be a type-Ia supernova well before maximum. The best fit to this spectrum found by the 'PASSparToo' supernova-spectra comparison tool (Harutyunyan et al. 2005, ASP Conf. Ser. 342, 258) is with the type-Ia supernova 1999dk at 13 days before maximum, though 2007gi shows a higher expansion velocity -- i.e., 20500 km/s, as measured from the Si II 635-nm feature, and adopting 1445 km/s for the host-galaxy recession velocity (Falco et al. 1999, PASP 111, 438). Also, the S II absortions, measured at 532 and 559 nm in the galaxy rest frame, are stronger.
- Publication:
-
Central Bureau Electronic Telegrams
- Pub Date:
- August 2007
- Bibcode:
- 2007CBET.1021....1H