Abstract
We report the results of a three-year-long dedicated monitoring campaign
of a restless luminous blue variable (LBV) in NGC 7259. The object,
named SN 2009ip, was observed photometrically and spectroscopically in
the optical and near-infrared domains. We monitored a number of erupting
episodes in the past few years, and increased the density of our
observations during eruptive episodes. In this paper, we present the
full historical data set from 2009 to 2012 with multi-wavelength dense
coverage of the two high-luminosity events between 2012 August and
September. We construct bolometric light curves and measure the total
luminosities of these eruptive or explosive events. We label them the
2012a event (lasting ~50 days) with a peak of 3 × 1041
erg s-1, and the 2012b event (14 day rise time, still
ongoing) with a peak of 8 × 1042 erg
s-1. The latter event reached an absolute R-band
magnitude of about -18, comparable to that of a core-collapse
supernova (SN). Our historical monitoring has detected high-velocity
spectral features (~13,000 km s-1) in 2011 September,
one year before the current SN-like event. This implies that the
detection of such high-velocity outflows cannot, conclusively, point to
a core-collapse SN origin. We suggest that the initial peak in the 2012a
event was unlikely to be due to a faint core-collapse SN. We propose
that the high intrinsic luminosity of the latest peak, the variability
history of SN 2009ip, and the detection of broad spectral lines
indicative of high-velocity ejecta are consistent with a pulsational
pair-instability event, and that the star may have survived the last
outburst. The question of the survival of the LBV progenitor star and
its future fate remain open issues, only to be answered with future
monitoring of this historically unique explosion.
Original language | English |
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Pages (from-to) | 1 |
Journal | The Astrophysical Journal |
Volume | 767 |
Publication status | Published - 01 Apr 2013 |
Keywords
- galaxies: individual: NGC 7259
- supernovae: general
- supernovae: individual: SN 2009ip SN 2000ch