| SN 2008S: A Cool Super-Eddington Wind in a Supernova Impostor (2008) | |||||||||
Abstract | |||||||||
| We present visual-wavelength photometry and spectroscopy of SN2008S. Based on the relatively low peak luminosity for a supernova (SN) of M_R = -13.9 mag and moderate outflow speeds of \la 600 km/s indicated by the spectrum, we find that SN2008S is not a true core-collapse SN or electron-capture SN. Instead, we interpret SN2008S as a "SN impostor" event much like SN1997bs, analogous to the giant eruptions of luminous blue variables. Its total radiated energy was ~10^47.8 ergs, and it may have ejected 0.05--0.2 Msun in the event. We note an uncanny similarity between the spectrum of SN2008S and that of the Galactic hypergiant IRC+10420, both of which are dominated by narrow H-alpha, [CaII], and CaII emission lines. We propose a scenario where the vastly super-Eddington (\Gamma \approx 40) wind of SN2008S partly fails because of a reduction in the electron-scattering opacity due to recombination. We favor a stellar mass of \ga 20 Msun, and speculate that this outburst may have implications for the progenitor of SN1987A.. Comment: 4 pages, 2 figs, submitted to ApJ Letters | |||||||||
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