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S. Z. Siloti (University of Oklahoma), E. M. Schlegel, P. Challis, S. Jha, R. P. Kirshner (Harvard-Smithsonian Center for Astrophysics), P. Garnavich (University of Notre Dame)
SN 1999E is an unusually luminous type IIn supernova that may have been associated with GRB 980910. Its spectrum most closely resembles those of the hypernovae SN IIn 1997cy and SN Ic 1998bw. These characteristics make it a possible hypernova. We examine photometric and spectroscopic data obtained for SN1999E to determine how it compares and contrasts contrasts with other SNe IIn. SN1999E's light curve decayed at a rate of 7.9 millimag day-1 in the B-band, 6.9 millimag day-1 in the V-band, and 7.7 millimag day-1 in the R-band. These values are not as slow as in other SNe IIn's. The spectra showed the characteristic narrow H\alpha emission line. Weak emission from H\beta was also present. Both H lines possessed broad components with FWHM ~ 100 - 200 Å\ during the first four months. Narrow emission lines of NII and possibly [OII] were also identified. SN1999E's spectra are very peculiar, having several extremely broad features overlapping each other. A spectrum obtained a year after discovery shows a flat, near-zero continuum with prominent, narrow emission lines of H, NII, and [OII] present, though at much lower fluxes than earlier spectra. These lines suggests the presence of an HII region, although whether it is interacting with the SN or is completely separate from the SN and only contaminating the spectra is not known.
This research was supported by the National Science Foundation's REU program.