SIMBAD references

J. Prieto, Ohio State University (OSU); P. Garnavich, University of Notre Dame; and D. DePoy, J. Marshall, J. Eastman, and S. Frank, OSU, on behalf of the SDSS-II Supernova Collaboration, report that spectra (range 390-730 nm; resolution 0.31 nm/pixel) of SN 2005gj (cf. CBET 247, IAUC 8616) were obtained with the MDM 2.4-m telescope (+ CCDS) approximately once per week since its discovery. The supernova was discovered by the SDSS-II supernova search and initially classified as a type-IIn event based on the presence of resolved Balmer emission. The spectrum has evolved to show broad absorption features at around 440, 475, 510, and 610 nm (rest-frame for z = 0.062), while the Balmer emission lines remain. The spectrum obtained on Nov. 12.3 UT is remarkably similar to the spectrum of the peculiar type-Ia supernova 2002ic (cf. IAUC 8019, 8151, 8157, 8161) obtained on 2002 Dec. 27 (Hamuy et al. 2003, Nature, 424, 651). It is concluded that SN 2005gj is a 1991T-like type-Ia event interacting with circumstellar material and giving rise to the resolved emission lines on top of the characteristic type-Ia spectrum. This is the second clear detection of hydrogen in the spectrum of a type-Ia supernova. The preliminary SDSS-II light curve indicates that it has just passed maximum light (at magnitude r about 17.2). The study of SN 2005gj throughout the electromagnetic spectrum is urged, as it could yield data to help to understand better the nature of the progenitors of thermonuclear supernovae. A plot comparing the spectrum of SN 2005gj with that of SN 2002ic has been posted at http://www.astronomy.ohio-state.edu/~prieto/sn05gj_compar.ps