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Breaking the Habit: The Peculiar 2016 Eruption of the Unique Recurrent Nova M31N 2008-12a

Henze, M. and Chinetti, K. and Masci, F. J. (2018) Breaking the Habit: The Peculiar 2016 Eruption of the Unique Recurrent Nova M31N 2008-12a. Astrophysical Journal, 857 (1). Art. No. 68. ISSN 1538-4357.

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Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multiwavelength properties: (i) from a faint peak, the optical light curve declined rapidly by two magnitudes in less than two days, (ii) early spectra showed initial high velocities that slowed down significantly within days and displayed clear He/N lines throughout, and (iii) the supersoft X-ray source (SSS) phase of the nova began extremely early, six days after eruption, and only lasted for about two weeks. In contrast, the peculiar 2016 eruption was clearly different. Here we report (i) the considerable delay in the 2016 eruption date, (ii) the significantly shorter SSS phase, and (iii) the brighter optical peak magnitude (with a hitherto unobserved cusp shape). Early theoretical models suggest that these three different effects can be consistently understood as caused by a lower quiescence mass accretion rate. The corresponding higher ignition mass caused a brighter peak in the free–free emission model. The less massive accretion disk experienced greater disruption, consequently delaying the re-establishment of effective accretion. Without the early refueling, the SSS phase was shortened. Observing the next few eruptions will determine whether the properties of the 2016 outburst make it a genuine outlier in the evolution of M31N 2008-12a.

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URLURL TypeDescription Paper
Henze, M.0000-0001-9985-3406
Masci, F. J.0000-0002-8532-9395
Additional Information:© 2018 The American Astronomical Society. Received 2017 November 24; revised 2018 February 27; accepted 2018 February 28; published 2018 April 16. We are deeply indebted to the late Swift PI Neil Gehrels for his long-term support of our project and for giving our community the game-changing Swift observatory. This paper is dedicated to his memory. We thank the anonymous referee for constructive comments that helped to improve the paper. We are, as always, grateful to the Swift Team for making the ToO observations possible, in particular to the duty scientists as well as the science planners. This research made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #14651. Support for program #14651 was provided by NASA through a grant from STScI. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University (LJMU) in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias with financial support from STFC. This work makes use of observations from the LCO network. Based (in part) on data collected with the Danish 1.54m telescope at the ESO La Silla Observatory. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. The HET is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia. The Pirka telescope is operated by the Graduate School of Science, Hokkaido University, and it also participates in the Optical & Near-Infrared Astronomy Inter-University Cooperation Program, supported by the MEXT of Japan. We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. The Institute for Gravitation and the Cosmos is supported by the Eberly College of Science and the Office of the Senior Vice President for Research at the Pennsylvania State University. We wish to thank G. Mansir for sharing her observing time at the 1.54 m Danish telescope on December 15th. We acknowledge G. Zeimann, who reduced the HET spectra. We thank T. Johnson for assisting in observations at MLO. We wish to acknowledge Lucía Suárez-Andrés (ING) for obtaining the INT observations on a Director's Discretionary Time night, generously awarded by Marc Balcells (ING) and Cecilia Fariña (INT) to our collaboration. M. Henze acknowledges the support of the Spanish Ministry of Economy and Competitiveness (MINECO) under the grant FDPI-2013-16933, the support of the Generalitat de Catalunya/CERCA programme, and the hospitality of the Liverpool John Moores University during collaboration visits. S.C.W. acknowledges a visiting research fellowship at Liverpool John Moores University. M.K. and I.H. acknowledge support in part by Grants in Aid for Scientific Research (15K05026, 16K05289) of the Japan Society for the Promotion of Science. G.C.A. and M.P. thank the HCT observers who spared part of their time for the observations. K.C. acknowledges support by the GROWTH project funded by the National Science Foundation under grant No. 1545949. M. Hernanz acknowledges MINECO support under the grant ESP2015_66134_R as well as the support of the Generalitat de Catalunya/CERCA program. K.H., H.K., and J.V. were supported by the project RVO:67985815. R.H. acknowledges support from the HST grant 14651. E.P. acknowledges support by the Ministry of Education of the Czech Republic (grant LG15010). V.A.R.M.R. acknowledges financial support from Fundação para a Ciência e a Tecnologia (FCT) in the form of an exploratory project of reference IF/00498/2015, from the Center for Research & Development in Mathematics and Applications (CIDMA) strategic project UID/MAT/04106/2013 and supported by Enabling Green E-science for the Square Kilometer Array Research Infrastructure (ENGAGESKA), POCI-01-0145-FEDER-022217, funded by Programa Operacional Competitividade e Internacionalização (COMPETE 2020) and FCT, Portugal. P.R.-G. acknowledges support by a Ramón y Cajal fellowship (RYC2010–05762). The use of Tom Marsh's pamela package is gratefully acknowledged. K. L.P. and J.P.O. acknowledge the support of the UK Space Agency. T.O. acknowledges support from U.S. NSF grant AST-1358787. S.S. acknowledges partial support to ASU from NASA and HST grants. This research has made use of the "Aladin Sky Atlas" developed at CDS, Strasbourg Observatory, France. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. PyRAF is a product of the Space Telescope Science Institute, which is operated by AURA for NASA. We wish to thank the Observatorio Astrofisico de Javalambre Data Processing and Archiving Unit (UPAD) for reducing and calibrating the JAST/T80 data. Facilities: AAVSO - American Association of Variable Star Observers International Database, ARC - , Danish 1.54m Telescope - , FTN - , HCT - , HET - , HST (WFC3) - , ING:Newton - , LBT - , LCO - , Liverpool:2m - , Mayall - , MLO:1m - , NOT - , OAO:0.5m - , OO:0.65 - , PO:1.2m - , ERAU:0.6m - , ERAU:1m - , Swift - , XMM - . Software: AIP4WIN, Aladin (v9; Bonnarel et al. 2000; Boch & Fernique 2014), APAS (Darnley et al. 2007), APHOT (Pravec et al. 1994), calwf3 (v3.4; Dressel 2012), DOLPHOT (v2.0; Dolphin 2000), FotoDif (v3.95), HEASOFT (v6.16), IRAF (v2.16 and v2.16.1, Tody 1993), MaxIm DL (v5.23), Mira Pro x64 (v8.011 and v8.012), Panacea, PGPLOT (v5.2), PyRAF, R (R Development Core Team 2011), SAOImage DS9, Starlink (v2016A, Disney & Wallace 1982), Source Extractor (v2.8.6; Bertin & Arnouts 1996), SWarp (v2.19.1 Bertin et al. 2002), XIMAGE (v4.5.1), XMM-SAS (v15.0.0), XSELECT (v2.4c), XSPEC (v12.8.2; Arnaud 1996).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASANAS 5-26555
Space Telescope Science InstituteUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Pennsylvania State UniversityUNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)FDPI-2013-16933
Generalitat de CatalunyaUNSPECIFIED
Liverpool John Moores UniversityUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)15K05026
Japan Society for the Promotion of Science (JSPS)16K05289
Ministerio de Economía, Industria y Competitividad (MINECO)ESP2015_66134_R
Academy of Sciences of the Czech RepublicRVO:67985815
NASA Hubble Fellowship14651
Ministry of Education of the Czech RepublicLG15010
Fundação para a Ciência e a Tecnologia (FCT)IF/00498/2015
Center for Research & Development in Mathematics and Applications (CIDMA)UID/MAT/04106/2013
Enabling Green E-science for the Square Kilometer Array Research Infrastructure (ENGAGESKA)POCI-01-0145-FEDER-022217
Fundação para a Ciência e a Tecnologia (FCT)COMPETE 2020
Ramón y Cajal ProgrammeRYC2010-05762
United Kingdom Space Agency (UKSA)UNSPECIFIED
Subject Keywords:galaxies: individual (M31) – novae, cataclysmic variables – stars: individual (M31N 2008-12a) – ultraviolet: stars – X-rays: binaries
Record Number:CaltechAUTHORS:20180416-154613187
Persistent URL:
Official Citation:M. Henze et al 2018 ApJ 857 68
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85885
Deposited By: Tony Diaz
Deposited On:16 Apr 2018 23:07
Last Modified:16 Apr 2018 23:07

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