SN 1961V - an extragalactic ETA Carinae analog

view Abstract Citations (110) References (75) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS SN 1961V: an Extragalactic Eta Carinae Analog? Goodrich, Robert W. ; Stringfellow, Guy S. ; Penrod, G. Donald ; Filippenko, Alexei V. Abstract We have obtained spectra of the site of the unique Type V supernova SN 1961V in NGC 1058, and of two nearby H II regions. Broad (FWHM ~ 2100 km s^-1^) Hα emission, with a luminosity of 2 x 10^36^ ergs s^-1^, is detected at the position of SN 1961V. SN 1961V is thus the first historical extragalactic object classified as a supernova to be optically recovered. The "east H II region," about 1.6" northeast of SN 1961V, is a small high-excitation H II region, with strong [O II], [N II], and [S II] lines for its excitation, and no detectable continuum. The temperature of the ionizing star must be greater than 45,000 K, but the H II region requires only a small fraction of the ionizing flux that such a star would produce. We argue that the east region is probably ionized by the SN 1961V progenitor, some 60 pc distant, and intercepts only a fraction of the ionizing flux from that star. The nearby "west H II region" is an intermediate-age supernova remnant, similar in its optical and radio properties to the most luminous supernova remnants in M31 and M33, but is not obviously associated with SN 1961V. We believe that SN 1961V was not a supernova (the explosion of a massive star at the end of its life) but the superoutburst of a luminous blue variable--an exaggerated η Carinae-type outburst of a very massive, evolved star near the end of core hydrogen burning. The long plateau in the light curve following outburst, at nearly the same brightness as the preoutburst star, suggests that the progenitor survived the outburst and was seen for more than 4 years afterward. It eventually faded because of the formation of optically thick dust in the ejecta, which amounts to only ~1-10 M_sun_. The progenitor is one of the most massive and luminous known stars, with a zero-age main-sequence (ZAMS) mass >~240 M_sun_ and a current mass >~170 M_sun_. The major reduction in mass is a direct result of mass lost during core hydrogen burning through a wind, and perhaps previous large episodic events. The hot underlying star should therefore now be of type Of/WN, like the S Doradus star R127 in the Large Magellanic Cloud but several times more luminous. During outburst the star had the spectrum and colors of an F supergiant, formed in an extended optically thick wind, and was thus optically very bright, partly at the expense of a changing bolometric correction. In addition, considerable thermal radiation was apparently liberated from the material ejected by the star, resulting in the energetic outburst observed. Such a star can account for both the high excitation of the nearby east H II region and the extreme visual brightness of the progenitor without requiring an unreasonably high mass or luminosity. Our observed Hα flux from the site of SN 1961V suggests a circumstellar extinction of A_v_ ~ 5 mag, if the surviving star resembles η Car. The present brightness of the star should be near V ~ 27 mag with a large uncertainty. The infrared brightness should be much higher. Publication: The Astrophysical Journal Pub Date: July 1989 DOI: 10.1086/167646 Bibcode: 1989ApJ...342..908G Keywords: H Ii Regions; Light Curve; Stellar Mass Ejection; Supermassive Stars; Supernova Remnants; H Alpha Line; Interstellar Extinction; Late Stars; Stellar Evolution; Stellar Luminosity; Variable Stars; Astrophysics; NEBULAE: H II REGIONS; STARS: MASS LOSS; STARS: MASSIVE; STARS: SUPERNOVAE; STARS: VARIABLES full text sources ADS | data products SIMBAD (12) NED (5)