학술논문
M31N 2008-12a-The Remarkable Recurrent Nova in M31-Panchromatic Observations of the 2015 Eruption
Document Type
Report
Author
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; Barsukova, E. A; Boumis, P; Chen, T; Fabrika, S; Figueira, J; Gao, X; Gehrels, N; Godon, P; Goranskij, V. P; Harman, D. J; Hartmann, D. H; Hosseinzadeh, G; Horst, J. Chuck; Itagaki, K; Jose, J; Kabashima, F; Kaur, A; Kawai, N; Kennea, J. A; Kiyota, S; KuČáková, H; Lau, K. M; Maehara, H; Naito, H; Nakajima, K; Nishiyama, K; O’Brien, T. J; Quimby, R; Sala, G; Sano, Y; Sion, E. M; Valeev, A. F; Watanabe, F; Watanabe, M; Williams, B. F; Xu, Z
Source
The Astrophysical Journal. 833(2)
Subject
Language
English
ISSN
2041-8213
2041-8205
2041-8205
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 approx. 13,000 km/s, 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.