J/ApJ/857/68 2016 eruption LC of the recurrent nova M31N 2008-12a (Henze+, 2018)
Breaking the habit: the peculiar 2016 eruption of the unique recurrent nova
M31N 2008-12a.
Henze M., Darnley M.J., Williams S.C., Kato M., Hachisu I., Anupama G.C.,
Arai A., Boyd D., Burke D., Ciardullo R., Chinetti K., Cook L.M., Cook M.J.,
Erdman P., Gao X., Harris B., Hartmann D.H., Hornoch K., Horst J.C.,
Hounsell R., Husar D., Itagaki K., Kabashima F., Kafka S., Kaur A.,
Kiyota S., Kojiguchi N., Kucakova H., Kuramoto K., Maehara H., Mantero A.,
Masci F.J., Matsumoto K., Naito H., Ness J.-U., Nishiyama K., Oksanen A.,
Osborne J.P., Page K.L., Paunzen E., Pavana M., Pickard R., Prieto-
Arranz J., Rodriguez-Gil P., Sala G., Sano Y., Shafter A.W., Sugiura Y.,
Tan H., Tordai T., Vrastil J., Wagner R.M., Watanabe F., Williams B.F.,
Bode M.F., Bruno A., Buchheim B., Crawford T., Goff B., Hernanz M.,
Igarashi A.S., Jose J., Motta M., O'Brien T.J., Oswalt T., Poyner G.,
Ribeiro V.A.R.M., Sabo R., Shara M.M., Shears J., Starkey D., Starrfield S.,
Woodward C.E.
<Astrophys. J., 857, 68 (2018)>
=2018ApJ...857...68H 2018ApJ...857...68H
ADC_Keywords: Photometry, UBVRI; Photometry, ugriz; Novae
Keywords: galaxies: individual (M31) ; novae, cataclysmic variables ;
stars: individual (M31N 2008-12a) ; ultraviolet: stars ;
X-rays: binaries
Abstract:
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.
Description:
A major achievement for the 2016 eruption campaign was the addition of
extensive observations from the American Association of Variable Star
Observers (AAVSO), along with the continued support of the Variable
Star Observers League in Japan (VSOLJ; see Section 3.1 and Appendix
A). Observations were also obtained from the Mount Laguna Observatory
(MLO) 1.0m telescope in California, the Ondrejov Observatory 0.65m
telescope in the Czech Republic, the Danish 1.54m telescope at La
Silla in Chile, the fully robotic 2m Liverpool Telescope (LT) in La
Palma, the 2.54m Isaac Newton Telescope (INT) at La Palma, the Palomar
48" telescope in California, the 0.6m and 1m telescopes operated by
members of the Embry Riddle Aeronautical University (ERAU) in Florida,
the 2x8.4m (11.8m eq.) Large Binocular Telescope (LBT) on Mount
Graham, Arizona, the 2m Himalayan Chandra Telescope (HCT) located at
Indian Astronomical Observatory (IAO), Hanle, India, and the 2.4m
Hubble Space Telescope.
The 2016 eruption and pre-eruption interval of M31N 2008-12a were
observed serendipitously by HST WFC3/UVIS as part of Program ID: 14651.
The spectroscopic confirmation of the 2016 eruption of M31N 2008-12a
was announced by Darnley+ (2016ATel.9852....1D 2016ATel.9852....1D), with additional
spectroscopic follow-up reported in Pavana & Anupama (2016ATel.9865....1P 2016ATel.9865....1P).
We obtained several spectra of the 2016 eruption with SPRAT, the
low-resolution, high-throughput spectrograph on the LT. SPRAT covers
the wavelength range of 4000-8000Å (resolution of ∼18Å).
We obtained an early spectrum of the nova, 0.54 days after eruption,
using the Andalucia Faint Object Spectrograph and Camera (ALFOSC) on
the 2.5m Nordic Optical Telescope (NOT) at the Roque de los Muchachos
Observatory on La Palma.
In addition, 1.87 days after eruption, we obtained a spectrum of M31N
2008-12a using the blue channel of the 10m Hobby Eberly Telescope's
(HET's) new integral-field Low Resolution Spectrograph (LRS2-B).
Two epochs of spectra were obtained using the Himalayan Faint Object
Spectrograph and Camera (HFOSC) mounted on the 2m HCT located at IAO,
Hanle, India.
Three spectra were obtained with the 3.5m Astrophysical Research
Consortium (ARC) telescope at the Apache Point Observatory, during the
first half of the night on 2016 December 12, 13, and 17 (UT December
13, 14, and 18).
A Neil Gehrels Swift Observatory target of opportunity (ToO) request
was submitted immediately after confirming the eruption, and the
satellite began observing the nova on 2016 December 12.65 UT.
In addition, we triggered a 100ks XMM-Newton ToO. The XMM-Newton
object ID is 078400.
In addition, we obtained UV data using the XMM-Newton optical/UV
monitor telescope.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
00 45 28.80 +41 54 10.1 M31N 2008-12a = PTF 09hsd
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table10.dat 114 291 Complete dataset of the visible and near infrared
photometric observations of the 2016 eruption of
M31N 2008-12a
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See also:
VIII/10 : Bell Laboratories H I Profiles (Stark+ 1992)
J/ApJ/609/735 : M31 Chandra X-ray sources (Williams+, 2004)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/A+A/465/375 : X-ray monitoring of optical novae in M31 (Pietsch+, 2007)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/ApJS/187/275 : Photometric histories of recurrent novae (Schaefer, 2010)
J/A+A/533/A52 : X-ray monitoring of M31 novae (Henze+, 2011)
J/ApJS/197/31 : Swift X-ray obs. of classical novae. II. (Schwarz+, 2011)
J/A+A/563/A2 : X-ray monitoring of M31 novae (Henze+, 2014)
J/A+A/580/A45 : Nova M31N 2008-12a 2014 eruption in opt/UV (Darnley+, 2015)
J/ApJ/833/149 : Opt/NIR obs. of M31N 2008-12a 2015 eruption (Darnley+, 2016)
J/ApJ/851/L21 : UV-NIR compilation of GW170817 counterpart (Villar+, 2017)
Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 4 I4 yr Obs.Y UT Observation date, Year
6- 7 I2 --- Obs.M UT Observation date, Month
9- 14 F6.3 d Obs.D UT Observation date, Fractional day
16- 21 F6.3 d dt [-5.3/27] Time since eruption (1)
23- 29 F7.3 d MJD Observation date, Modified Julian date;
JD-2457000.5
31- 37 F7.3 d MJD-Start ? Start of observation, where available,
Modified Julian date; JD-2457000.5
39- 45 F7.3 d MJD-End ? End of observation, where available,
Modified Julian date; JD-2457000.5
47- 79 A33 --- Tel Telescope + Instrument (2)
81- 87 A7 s Exp Exposure, time or sequence (coadd x time)
89- 96 A8 --- Filt Broadband Filter (3)
97- 97 A1 --- l_omag Limit flag for omag
99-104 F6.3 mag omag [16.3/24.2] Observed magnitude in Filt
106-110 F5.3 mag e_omag [0.01/0.5]? Uncertainty in omag
112-114 A3 --- r_omag [ ,a-k] Photometry Reference(s) (4)
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Note (1): The time since eruption assumes an eruption date of
2016 December 12.32 UT.
Note (2): Instrument as follows:
INT WFC = The 2.54m Isaac Newton Telescope (INT) at La Palma.
ERAU = Embry Riddle Aeronautical University (ERAU), Florida;
see Appendix A.4.
LT IO:O = The fully robotic 2 m Liverpool Telescope (LT) in
La Palma.
HST WFC3/UVIS = HST program ID: 14651; see section 2.1.1.
AAVSO HBB = We obtained light curve photometry using a Meade 0.4m
SCT located at New Smyrna Beach, FL; see Appendix A.20.
AAVSO COO = We observed M31N 2008-12a with the CBA Concord PF29
telescope (0.74m reflector) located in suburban Concord,
CA; see Appendix A.13 and A.14.
AAVSO BDG = We obtained observations at West Challow Observatory,
Oxfordshire, UK, on most clear nights using a 0.35m
Meade Schmidt-Cassegrain Telescope; see Appendix A.17.
AAVSO OAR = Pre-eruption upper limits were obtained at Hankasalmi
Observatory, Finland using a 0.4m RC (RCOS) telescope;
see Appendix A.12.
AAVSO PXR = We observed the nova using a 0.4m SCT telescope located
on Haleakala, Hawaii, as part of the LCO group;
see Appendix A.19.
AAVSO MAND = Light curve photometry was obtained at Bernezzo
Observatory, Italy, using a 0.25m reflector;
see Appendix A.18.
AAVSO CMJA = The Newcastle Observatory in Newcastle, Ontario, Canada
using a 0.40m Meade Schmidt-Cassegrain (ACF) Telescope;
see Appendix A.15.
MLO = The Mount Laguna Observatory (MLO) 1.0m telescope in
California.
Xingming HMT = Xingming Observatory Half-meter Telescope (HMT);
see Appendix A.2.
HCT HFOSC = The 2m Himalayan Chandra Telescope (HCT);
see Appendix A.3.
Danish 1.54m = The Danish 1.54m telescope at the ESO La Silla
Observatory; see Appendix A.5.
ROTAT = ROTAT is a 0.60m Newtonian reflector located at the
Observatoire de Haute Provence, France; see A.23.
LBT MODS2R = We obtained optical images and photometry of
M31N 2008-12a on 2017 January 08.12 UT with the 8.4m
LBT and Multi-Object Double Spectrograph (MODS2);
see Appendix A.16.
Ondrejov 0.65m = The Ondrejov Observatory 0.65m telescope in the Czech
Republic
Osaka Kyoiku University = the 0.51m telescope of the Osaka Kyoiku
University, Japan; see Appendix A.8.
Palomar 48" = The Palomar 48" telescope in California.
Pirka 1.6m = The Nayoro Observatory 1.6m Pirka telescope
(Naito+ 2016ATel.9891....1N 2016ATel.9891....1N)
Kiso Observatory = We obtained V-band CCD images with the 1.05m Schmidt
telescope equipped with the Kiso Wide Field Camera of
the Kiso Observatory, University of Tokyo, Japan;
see Appendix A.6.
AstroCamp Observatory = Monitoring data was reported first by
Naito+ (2016ATel.9891....1N 2016ATel.9891....1N) based on remote
observations with the following instruments:
(a) a 0.5m CDK astrograph at the New Mexico Skies
site (Mayhill, NM),
(b) a 0.43m CDK astrograph at the AstroCamp
Observatory hosting site (Nerpio, Spain), and
(c) a 0.32m CDK astrograph at the AstroCamp
Observatory. See Appendix A.11.
Meili 0.4m = The 0.4m Meili telescope (Meade Schmidt-Cassegrain
Telescope) at Nayoro Observatory, Japan;
see Appendix A.10.
Okayama Astrophysical Observatory = the 0.5m MITSuME telescope of the
Okayama Astrophysical Observatory, Japan; see A.7.
Miyaki-Argenteus = The 0.5m telescope at the Miyaki-Argenteus Observatory,
Japan; see Appendix A.9.
Itagaki Observatory = Additional light curve photometry was first reported
in Naito+ (2016ATel.9891....1N 2016ATel.9891....1N); see Appendix A.1.
Itagaki 50cm = The 2016 eruption was discovered by
Itagaki+ (2016ATel.9848....1I 2016ATel.9848....1I); see Appendix A.1.
SATINO-2 = SATINO-2 telescope located at the Observatoire de
Haute Provence, France; see Appendix A.23.
Polaris Observatory = Images were obtained at the Polaris Observatory,
Budapest, Hungary, using a 0.25m Newtonian reflector;
see Appendix A.21.
OAJ = The JAST/T80 telescope at the Observatorio Astrofisico
de Javalambre, in Teruel; see Appendix A.22.
Note (3): A value of "--" for the Filter column indicates that the photometry
was unfiltered.
Note (4): This table includes all observations from t∼7days before the
eruption including preliminary photometry published as the optical light
curve was evolving. Photometry References as follows:
a = Naito et al. (2016ATel.9891....1N 2016ATel.9891....1N);
b = Itagaki et al. (2016ATel.9848....1I 2016ATel.9848....1I);
c = Tan et al. (2016ATel.9885....1T 2016ATel.9885....1T);
d = Shafter et al. (2016ATel.9864....1S 2016ATel.9864....1S);
e = Burke et al. (2016ATel.9861....1B 2016ATel.9861....1B);
f = Hornoch et al. (2016ATel.9883....1H 2016ATel.9883....1H);
g = Darnley et al. (2016ATel.9906....1D 2016ATel.9906....1D);
h = Darnley (2016ATel.9910....1D 2016ATel.9910....1D);
i = Erdman et al. (2016ATel.9857....1E 2016ATel.9857....1E);
j = Kaur et al. (2016ATel.9881....1K 2016ATel.9881....1K);
k = Darnley & Hounsell (2016ATel.9874....1D 2016ATel.9874....1D).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Feb-2019