F. Patat, European Southern Observatory (ESO); J. Maza, Universidad de Chile; S. Benetti, Telescopio Nazionale Galileo, Centro Galileo Galilei, Santa Cruz de La Palma; and E. Cappellaro, Padova Observatory, write: "We have observed SN 1999ca (cf. IAUC 7158) with the ESO New Technology Telescope (+ EMMI; range 340-1000 nm, resolution 1.0 nm) on May 7.05 UT at La Silla. A full reduction of the CCD spectrogram shows that this is a type-II supernova around one month after maximum light. H-alpha, H-beta, H-gamma, and H-delta, superimposed on a continuum that peaks around 550 nm, are clearly visible. The H-alpha line is quite asymmetric, with possible unresolved structures, and its P-Cyg absorption is very weak. Besides the Balmer series, the most prominent features are identified as Ca II, Ba II, Fe I, Na I, and Ca II. The expansion velocities, deduced from the absorption minima, are 6800, 7600, and 6400 km/s for Ca II H and K, Na I D, and H-alpha, respectively. Two unresolved absorptions of Na I D are clearly visible; one is at the parent-galaxy rest-frame velocity (2791 km/s; Theureau et al. 1998, A.Ap. Suppl. 130, 333), while the other absorption most likely originates in the Milky Way. The total equivalent widths are 0.27 and 0.13 nm for the two Na features, respectively."
International Astronomical Union Circular
- Pub Date:
- May 1999