Darnley, MJ, Henze, M, Bode, MF, Hachisu, I, Hernanz, M, Hornoch, K, Hounsell, R, Kato, M, Ness, J-U, Osborne, JP, Page, KL, Ribeiro, VARM, Rodriguez-Gil, P, Shafter, AW, Shara, MM, Steele, IA, Williams, SC, Arai, A, Arcavi, I, Barsukova, EA et al, Boumis, P, Chen, T, Fabrika, S, Figueira, J, Gao, X, Gehrels, N, Godon, P, Goranskij, VP, Harman, DJ, Hartmann, DH, Hosseinzadeh, G, Horst, JC, Itagaki, K, Jose, J, Kabashima, F, Kaur, A, Kawai, N, Kennea, JA, Kiyota, S, Kucakova, H, Lau, KM, Maehara, H, Naito, H, Nakajima, K, Nishiyama, K, O'Brien, TJ, Quimby, R, Sala, G, Sano, Y, Sion, EM, Valeev, AF, Watanabe, F, Watanabe, M, Williams, BF and Xu, Z (2016) M31N 2008-12a - the remarkable recurrent nova in M31: Pan-chromatic observations of the 2015 eruption. Astrophysical Journal, 833 (2). ISSN 0004-637X

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Abstract

The Andromeda Galaxy recurrent nova M31N 2008-12a had been observed in eruption ten times, including yearly eruptions from 2008-2014. With a measured recurrence period of $P_\mathrm{rec}=351\pm13$ 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 2m (Hawaii) discovered the 2015 eruption, estimated to have commenced at Aug. $28.28\pm0.12$ UT. The 2013-2015 eruptions are remarkably similar at all wavelengths. New early spectroscopic observations reveal short-lived emission from material with velocities $\sim13000$ 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 super-soft 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 $P_\mathrm{rec}=174\pm10$ d, and we expect the next eruption of M31N 2008-12a to occur around mid-Sep. 2016.

Item Type:	Article
Uncontrolled Keywords:	astro-ph.SR; astro-ph.SR; astro-ph.HE
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society; IOP Publishing
Related URLs:	http://arxiv.org/abs/1607.08082v2
Date Deposited:	09 Sep 2016 14:58
Last Modified:	04 Sep 2021 12:32
DOI or ID number:	10.3847/1538-4357/833/2/149
URI:	https://researchonline.ljmu.ac.uk/id/eprint/4126

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