TY - JOUR

T1 - A remarkable recurrent nova in M 31

T2 - the optical observations

AU - Darnley, M. J.

AU - Williams, S. C.

AU - Bode, M. F.

AU - Henze, M.

AU - Ness, J.-u.

AU - Shafter, A. W.

AU - Hornoch, K.

AU - Votruba, V.

PY - 2014/3/1

Y1 - 2014/3/1

N2 - Context. In late Nov. 2013 the fifth eruption in five years of the M 31 recurrent nova M 31N 2008-12a was announced. Aims: In this Letter we address the optical lightcurve and progenitor system of M 31N 2008-12a. Methods: Optical imaging data of the 2013 eruption from the Liverpool Telescope, La Palma; Danish 1.54 m Telescope, La Silla; and archival Hubble Space Telescope near-IR, optical, and near-UV data are astrometrically and photometrically analysed. Results: Photometry of the 2013 eruption, combined with three previous eruptions, enabled construction of a template lightcurve of a very fast nova (t2(V)≃4 days). The archival data allowed recovery of the progenitor system in optical and near-UV data, indicating a red-giant secondary with bright accretion disk, or alternatively a system with a sub-giant secondary but dominated by a disk. Conclusions: The eruptions of M 31N 2008-12a, and a number of historic X-ray detections, indicate a unique system with a recurrence timescale of ~1 yr. This implies the presence of a very high-mass white dwarf and a high accretion rate. The recovered progenitor system is consistent with such an elevated rate of accretion. We encourage additional observations, especially towards the end of 2014.

AB - Context. In late Nov. 2013 the fifth eruption in five years of the M 31 recurrent nova M 31N 2008-12a was announced. Aims: In this Letter we address the optical lightcurve and progenitor system of M 31N 2008-12a. Methods: Optical imaging data of the 2013 eruption from the Liverpool Telescope, La Palma; Danish 1.54 m Telescope, La Silla; and archival Hubble Space Telescope near-IR, optical, and near-UV data are astrometrically and photometrically analysed. Results: Photometry of the 2013 eruption, combined with three previous eruptions, enabled construction of a template lightcurve of a very fast nova (t2(V)≃4 days). The archival data allowed recovery of the progenitor system in optical and near-UV data, indicating a red-giant secondary with bright accretion disk, or alternatively a system with a sub-giant secondary but dominated by a disk. Conclusions: The eruptions of M 31N 2008-12a, and a number of historic X-ray detections, indicate a unique system with a recurrence timescale of ~1 yr. This implies the presence of a very high-mass white dwarf and a high accretion rate. The recovered progenitor system is consistent with such an elevated rate of accretion. We encourage additional observations, especially towards the end of 2014.

U2 - 10.1051/0004-6361/201423411

DO - 10.1051/0004-6361/201423411

M3 - Journal article

VL - 563

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - L9

ER -