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Authors: 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. C.
Itagaki, K.
José, 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.
First Published: 13-Dec-2016
Publisher: American Astronomical Society, IOP Publishing
Citation: Astrophysical Journal, 833:149 (38pp), 2016 December 20
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.
DOI Link: 10.3847/1538-4357/833/2/149
ISSN: 0004-637X
eISSN: 1538-4357
Version: Post-print
Status: Peer-reviewed
Type: Journal Article
Rights: Creative Commons “Attribution Non-Commercial No Derivatives” licence CC BY-NC-ND, further details of which can be found via the following link: Archived with reference to SHERPA/RoMEO and publisher website.
Description: Facilities: Liverpool:2 m, FTN, OO:0.65, MLO:1 m, BAT, OAO:0.5 m, Swift, Mayall. Software: IRAF (v2.16.1; Tody 1993), Starlink (v2015B; Disney & Wallace 1982), APHOT (Pravec et al. 1994), HEASOFT (v6.16), XIMAGE (v4.5.1), XSPEC (v12.8.2; Arnaud 1996), XSELECT (v2.4c), R (R Development Core Team 2011).
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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