[] Spectroscopic observations of bright Type Ic supernova 2007gr


We performed spectroscopic observations of bright supernova (SN) 2007gr. There is no hydrogen and helium line in early spectra, and the SiII6355 line absorption is shallow, which suggested that SN 2007gr is a Type Ic SN. We also confirmed strong absorptions of OI7773 and Ca IR triplet in ealry spectra, which these lines is blue-shifted due to the fast expanding photosphere.

At late phase, the hydrogen emission lines become strong at 6500A, which doesn't come from SN, it would be originated from HII region in host galaxy. The OI and CaII line emission is seen at 6300A and 7400A, respectively. The OI line may be double-peaked structure, the red component would be strong at least. The observational fact suggested that the ring-like structure material would be ejected at inner region of SN 2007gr.