301 research outputs found
The Great Eruption of Eta Carinae
During the years 1838-1858, the very massive star {\eta} Carinae became the
prototype supernova impostor: it released nearly as much light as a supernova
explosion and shed an impressive amount of mass, but survived as a star.1 Based
on a light-echo spectrum of that event, Rest et al.2 conclude that "a new
physical mechanism" is required to explain it, because the gas outflow appears
cooler than theoretical expectations. Here we note that (1) theory predicted a
substantially lower temperature than they quoted, and (2) their inferred
observational value is quite uncertain. Therefore, analyses so far do not
reveal any significant contradiction between the observed spectrum and most
previous discussions of the Great Eruption and its physics.Comment: To appear in Nature, a brief communication arising in response to
Rest et al. 2012. Submitted to Nature February 17, 201
A Tale of Two Impostors: SN2002kg and SN1954J in NGC 2403
We describe new results on two supernova impostors in NGC 2403, SN 1954J(V12)
and SN 2002kg(V37). For the famous object SN 1954J we combine four critical
observations: its current SED, its Halpha emission line profile, the Ca II
triplet in absorption in its red spectrum, and the brightness compared to its
pre-event state. Together these strongly suggest that the survivor is now a hot
supergiant with T ~ 20000 K, a dense wind, substantial circumstellar
extinction, and a G-type supergiant companion. The hot star progenitor of V12's
giant eruption was likely in the post-red supergiant stage and had already shed
a lot of mass. V37 is a classical LBV/S Dor variable. Our photometry and
spectra observed during and after its eruption show that its outburst was an
apparent transit on the HR Diagram due to enhanced mass loss and the formation
of a cooler, dense wind. V37 is an evolved hot supergiant at ~10^6 Lsun with a
probable initial mass of 60 -80 Msun.Comment: To appear in the Astrophysical Journa
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