Sn 2010kd -- A Super-luminous, Pair-instability Supernova?
Abstract
SN 2010kd was discovered by the ROTSE Supernova Verification Project in a faint, metal-poor dwarf galaxy at z=0.101. The first optical spectra, obtained with the Hobby-Eberly Telescope, showed weak, broad SN-like features superimposed on a blue continuum. Modeling the early spectra with SYNOW identified no H or He, but CII, OI and OII, revealing that SN 2010kd is a peculiar Type Ic SN. A strong UV deficit in the early spectra can be fit with Co III. The spectrum and light curve exhibited unusually slow evolution. Peak brightness in the optical, corresponding to -21.1 mag absolute, occurred about 40 days after discovery After peak brightness, the spectrum slowly developed strong features of OI, OII, MgII, and FeII, and became very similar to the spectrum of SN 2007bi, a candidate Pair-Instability SN (PISN) event. The latest spectrum obtained with Keck at +192 days after peak still showed strong, broad photospheric features, consistent with the observed slow evolution of SN 2007bi. Comparison of the observed rise time to maximum with simple radioactive decay photon diffusion models gives an estimated ejecta mass of 23 Msun, and a nickel mass of 10 Msun. These parameters are more tightly constrained than in the case of SN 2007bi, because our light curve covers the pre-maximum phases much better. The derived Ni-mass favors a PISN event, but the ejecta mass seems to be too low compared to the prediction of such models ( 100 Msun), challenging the proposition that PISN is the explosion mechanism of SN 2010kd.
- Publication:
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American Astronomical Society Meeting Abstracts #219
- Pub Date:
- January 2012
- Bibcode:
- 2012AAS...21943604V