AT 2016blu: Accretion-powered Outbursts in a Luminous Blue Variable and Compact Object Binary

@article{aghakhanloo20262016blu,
  title = {{AT 2016blu: Accretion-powered Outbursts in a Luminous Blue Variable and Compact Object Binary}},
  author = {Mojgan Aghakhanloo and Núria Torres-Albà and Nathan Smith and Raphael Baer-Way and Shazrene Mohamed and Alexei V. Filippenko and WeiKang Zheng and Thomas G. Brink and D. Andrew Howell and Brian Hsu and Moira Andrews and Joseph R. Farah and Curtis McCully and Kathryn Wynn and Réka Könyves-Tóth and Conor L. Ransome and Enrique Rathmann and Tamás Tordai and Sjoerd Dufoer and Charles Cynamon and Franz-Josef Hambsch and Thomas Rutherford and Simone Leonini and Franky Dubois and Ivo Peretto and Donald F. Collins and Lorenzo Betti and Lara Fossi and Irene Parenti and Vincenzo Pettina and Giulio Giordano Chiti and Maria Hofheinz and André Steenkamp and Sauro Gaudenzi and Nikola Antonov and Giuseppe Pappa},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = nov,
  doi = {10.3847/1538-4357/ae9a86},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/ae9a86},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - AT 2016blu: Accretion-powered Outbursts in a Luminous Blue Variable and Compact Object Binary
AU  - Mojgan Aghakhanloo
AU  - Núria Torres-Albà
AU  - Nathan Smith
AU  - Raphael Baer-Way
AU  - Shazrene Mohamed
AU  - Alexei V. Filippenko
AU  - WeiKang Zheng
AU  - Thomas G. Brink
AU  - D. Andrew Howell
AU  - Brian Hsu
AU  - Moira Andrews
AU  - Joseph R. Farah
AU  - Curtis McCully
AU  - Kathryn Wynn
AU  - Réka Könyves-Tóth
AU  - Conor L. Ransome
AU  - Enrique Rathmann
AU  - Tamás Tordai
AU  - Sjoerd Dufoer
AU  - Charles Cynamon
AU  - Franz-Josef Hambsch
AU  - Thomas Rutherford
AU  - Simone Leonini
AU  - Franky Dubois
AU  - Ivo Peretto
AU  - Donald F. Collins
AU  - Lorenzo Betti
AU  - Lara Fossi
AU  - Irene Parenti
AU  - Vincenzo Pettina
AU  - Giulio Giordano Chiti
AU  - Maria Hofheinz
AU  - André Steenkamp
AU  - Sauro Gaudenzi
AU  - Nikola Antonov
AU  - Giuseppe Pappa
PY  - 2026
DA  - 2026/11/09
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/ae9a86
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/ae9a86
AB  - We present the first X-ray detection of the supernova (SN) impostor AT 2016blu in NGC 4559. AT 2016blu exhibited 27 detected quasiperiodic (∼113 day) outbursts between 2012 and 2026 June, presumably triggered by periastron passages in an eccentric binary system in which the primary is a ≳33 M ⊙ luminous blue variable (LBV). AT 2016blu was serendipitously observed by Chandra in 2001–2002, prior to its first documented outburst in 2012, but the stacked archival data show no X-ray detection. We monitored the source’s visual-wavelength variability around its predicted outburst time and triggered a Chandra Target of Opportunity (ToO) program in 2026 March, obtaining observations with detections over five closely spaced epochs. These data indicate an X-ray luminosity of log L X ≈ 38.64 ± 0.11 erg s ⁻¹ and an accretion rate of M ̇ ≳ 8 × 1 0 − 8 M ⊙ yr − 1 , consistent with the presence of a compact companion. We therefore conclude that AT 2016blu is the first known case of an LBV SN impostor where X-ray observations clearly favor intermittent accretion onto a compact object as the cause of the outbursts. Given that the system consists of a massive star and a compact companion, AT 2016blu is a high-mass X-ray binary (HMXB), similar to SN 2010da, although the donor star in SN 2010da is a red supergiant (RSG).
SN  - 1538-4357
SN  - 0004-637X
ER  -