Connecting the progenitors, pre-explosion variability and giant outbursts of luminous blue variables with Gaia16cfr

Charles D. Kilpatrick, Ryan J. Foley, Maria R. Drout, Yen Chen Pan, Fiona H. Panther, David A. Coulter, Alexei V. Filippenko, G. Howard Marion, Anthony L. Piro, Armin Rest, Ivo R. Seitenzahl, Giovanni Strampelli, Xi E. Wang

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

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 × 10-6M 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 Hα, 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.

Original languageEnglish
Pages (from-to)4805-4823
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Volume473
Issue number4
DOIs
StatePublished - 1 Feb 2018

Keywords

  • Instabilities
  • Outflows
  • Stars: evolution
  • Stars: mass loss
  • Stars: winds

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