2018MNRAS.473.4805K -
Mon. Not. R. Astron. Soc., 473, 4805-4823 (2018/February-1)
Connecting the progenitors, pre-explosion variability and giant outbursts of luminous blue variables with Gaia16cfr.
KILPATRICK C.D., FOLEY R.J., DROUT M.R., PAN Y.-C., PANTHER F.H., COULTER D.A., FILIPPENKO A.V., MARION G.H., PIRO A.L., REST A., SEITENZAHL I.R., STRAMPELLI G. and WANG X.E.
Abstract (from CDS):
We present multi-epoch, multicolour pre-outburst photometry and post-outburst light curves and spectra of the luminous blue variable (LBV) outburst Gaia16cfr discovered by the Gaia satellite on 2016 December 1 UT. We detect Gaia16cfr in 13 epochs of Hubble Space Telescope imaging spanning phases of 10 yr to 8 months before the outburst and in Spitzer Space Telescope imaging 13 yr before outburst. Pre-outburst optical photometry is consistent with an 18 M☉ F8 I star, although the star was likely reddened and closer to 30 M☉. The pre-outburst source exhibited a significant near-infrared excess consistent with a 120 au shell with 4 x 10–6 M☉ of dust. We infer that the source was enshrouded by an optically thick and compact shell of circumstellar material from an LBV wind, which formed a pseudo-photosphere consistent with S Dor-like variables in their 'maximum' phase. Within a year of outburst, the source was highly variable on 10-30 d time-scales. The outburst light curve closely matches that of the 2012 outburst of SN 2009ip, although the observed velocities are significantly slower than in that event. In H α, the outburst had an excess of blueshifted emission at late times centred around -1500 km s–1, similar to that of double-peaked Type IIn supernovae and the LBV outburst SN 2015bh. From the pre-outburst and post-outburst photometry, we infer that the outburst ejecta are evolving into a dense, highly structured circumstellar environment from precursor outbursts within years of the 2016 December event.
Abstract Copyright:
© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
instabilities - stars: evolution - stars: mass loss - stars: winds, outflows
Simbad objects:
37
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