M31N 2008-12a - The REMARKABLE RECURRENT NOVA in M31: PANCHROMATIC OBSERVATIONS of the 2015 ERUPTION

M. J. Darnley, M. Henze, M. F. Bode, I. Hachisu, M. Hernanz, K. Hornoch, R. Hounsell, Mariko Kato, J. U. Ness, J. P. Osborne, K. L. Page, V. A R M Ribeiro, P. Rodríguez-Gil, A. W. Shafter, M. M. Shara, I. A. Steele, S. C. Williams, A. Arai, I. Arcavi, E. A. BarsukovaP. Boumis, T. Chen, S. Fabrika, J. Figueira, X. Gao, N. Gehrels, P. Godon, V. P. Goranskij, D. J. Harman, D. H. Hartmann, G. Hosseinzadeh, J. Chuck Horst, K. Itagaki, J. José, F. Kabashima, A. Kaur, N. Kawai, J. A. Kennea, S. Kiyota, H. Kučáková, K. M. Lau, H. Maehara, H. Naito, K. Nakajima, K. Nishiyama, T. J. O'Brien, R. Quimby, G. Sala, Y. Sano, E. M. Sion, A. F. Valeev, F. Watanabe, M. Watanabe, B. F. Williams, Z. Xu

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Abstract

The Andromeda Galaxy recurrent nova M31N 2008-12a had been observed in eruption 10 times, including yearly eruptions from 2008 to 2014. With a measured recurrence period of Prec = 351 ± 13 days (we believe the true value to be half of this) and a white dwarf very close to the Chandrasekhar limit, M31N 2008-12a has become the leading pre-explosion supernova type Ia progenitor candidate. Following multi-wavelength follow-up observations of the 2013 and 2014 eruptions, we initiated a campaign to ensure early detection of the predicted 2015 eruption, which triggered ambitious ground- and space-based follow-up programs. In this paper we present the 2015 detection, visible to near-infrared photometry and visible spectroscopy, and ultraviolet and X-ray observations from the Swift observatory. The LCOGT 2 m (Hawaii) discovered the 2015 eruption, estimated to have commenced at August 28.28 ± 0.12 UT. The 2013-2015 eruptions are remarkably similar at all wavelengths. New early spectroscopic observations reveal short-lived emission from material with velocities ∼13,000 km s-1, possibly collimated outflows. Photometric and spectroscopic observations of the eruption provide strong evidence supporting a red giant donor. An apparently stochastic variability during the early supersoft X-ray phase was comparable in amplitude and duration to past eruptions, but the 2013 and 2015 eruptions show evidence of a brief flux dip during this phase. The multi-eruption Swift/XRT spectra show tentative evidence of high-ionization emission lines above a high-temperature continuum. Following Henze et al. (2015a), the updated recurrence period based on all known eruptions is Prec = 174 ± 10 days, and we expect the next eruption of M31N 2008-12a to occur around 2016 mid-September.

Original languageEnglish
Article number149
JournalAstrophysical Journal
Volume833
Issue number2
DOIs
Publication statusPublished - 2016 Dec 20

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Keywords

  • galaxies: individual (M31)
  • novae, cataclysmic variables
  • stars: individual (M31N 2008-12a)
  • ultraviolet: stars
  • X-rays: binaries

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Darnley, M. J., Henze, M., Bode, M. F., Hachisu, I., Hernanz, M., Hornoch, K., Hounsell, R., Kato, M., Ness, J. U., Osborne, J. P., Page, K. L., Ribeiro, V. A. R. M., Rodríguez-Gil, P., Shafter, A. W., Shara, M. M., Steele, I. A., Williams, S. C., Arai, A., Arcavi, I., ... Xu, Z. (2016). M31N 2008-12a - The REMARKABLE RECURRENT NOVA in M31: PANCHROMATIC OBSERVATIONS of the 2015 ERUPTION. Astrophysical Journal, 833(2), [149]. https://doi.org/10.3847/1538-4357/833/2/149