J/AJ/149/95 Photometry of nova LMC 2012 (Schwarz+, 2015)
Pan-chromatic observations of the remarkable nova Large Magellanic Cloud 2012.
Schwarz G.J., Shore S.N., Page K.L., Osborne J.P., Beardmore A.P.,
Walter F.M., Bode M.F., Drake J.J., Ness J.-U., Starrfield S.,
Van Rossum D.R., Woodward C.E.
<Astron. J., 149, 95 (2015)>
=2015AJ....149...95S 2015AJ....149...95S
ADC_Keywords: Magellanic Clouds ; Novae ; Photometry, UBVRI ;
Photometry, infrared
Keywords: novae, cataclysmic variables - ultraviolet: stars
Abstract:
We present the results of an intensive multiwavelength campaign on
nova LMC 2012. This nova evolved very rapidly in all observed
wavelengths. The time to fall two magnitudes in the V band was only
2days. In X-rays the super soft phase began 13±5days after discovery
and ended around day 50 after discovery. During the super soft phase,
the Swift/XRT and Chandra spectra were consistent with the underlying
white dwarf (WD) being very hot, ∼1MK, and luminous, ∼1038erg/s. The
UV, optical, and near-IR photometry showed a periodic variation after
the initial and rapid fading had ended. Timing analysis revealed a
consistent 19.24±0.03hr period in all UV, optical, and near-IR bands
with amplitudes of ∼0.3mag which we associate with the orbital period
of the central binary. No periods were detected in the corresponding
X-ray data sets. A moderately high inclination system, i=60±10°,
was inferred from the early optical emission lines. The HST/STIS UV
spectra were highly unusual with only the N v (1240Å) line present
and superposed on a blue continuum. The lack of emission lines and the
observed UV and optical continua from four epochs can be fit with a
low mass ejection event, ∼10-6M☉, from a hot and massive WD
near the Chandrasekhar limit. The WD, in turn, significantly
illuminated its subgiant companion which provided the bulk of the
observed UV/optical continuum emission at the later dates. The
inferred extreme WD characteristics and low mass ejection event favor
nova LMC 2012 being a recurrent nova of the U Sco subclass.
Description:
Nova LMC 2012 was discovered on March 26.397 UT (MJD56012.897) at a
visual magnitude of 10.7 (Seach et al., 2012CBET.3071....1S 2012CBET.3071....1S). After
discovery, LMC 2012 was observed by a number of different facilities
at a variety of wavelengths. The discovery date is taken as day zero
and the shorthand "Dn," where "n" is the number of days after day
zero, is used here.
Swift is a revolutionary facility for studying novae (see Schwarz et
al. 2011, cat. J/ApJS/197/31, for details). Its three instruments
cover the γ-ray (BAT), X-ray (XRT), plus UV and optical (UVOT)
bandpasses. Swift obtained 74 uvm2 band (λeff=2246Å,
FWHM=498Å) observations of LMC 2012 with the UVOT instrument from
D1.2 until D671. There were also 12 uvw2 band (λeff=1928Å,
FWHM=657Å) and nine uvw1 band (λeff=2600Å,
FWHM=693Å) observations which were only obtained early on D1.2 and
later during the observations after D300. The UVOT photometry is
provided in Table2.
LMC 2012 was extensively observed photometrically between D0.6 and
D635 with the Small & Moderate Aperture Research Telescope System
(SMARTS) at Cerro Tololo (see Walter et al., 2012PASP..124.1057W 2012PASP..124.1057W, for
details). We obtained 250 photometric observations in BVRI/JHK from
SMARTS. The optical photometry is supplemented with 54 early time CCD
BVRI observations from the American Association of Variable Star
Observers (AAVSO). The optical and near-infrared photometry is also
given in Table2.
Objects:
----------------------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
----------------------------------------------------------------------------
04 54 56.80 -70 26 56.6 NOVA LMC 2012 = LMCN 2012-03a (P=19.24±0.03hr)
----------------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 44 459 UV, optical, and IR photometry
table3.dat 69 71 Swift/XRT 0.3-10keV count rate and hardness ratio
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See also:
II/288 : IRSF Magellanic Clouds Point Source Catalog (Kato+ 2007)
I/305 : The Guide Star Catalog, Version 2.3.2 (GSC2.3) (STScI, 2006)
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
J/ApJS/197/31 : Swift X-ray observations of novae. II. (Schwarz+, 2011)
J/AJ/128/1606 : Magellanic Clouds Photometric Survey: the LMC (Zaritsky+, 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- Flt Filter used in the observation (BVRI, JHK, m2,
w1, w2) (1)
4- 10 F7.3 d Dt [0.5/672] Time since discovery (G1)
12- 20 F9.3 d MJD [56012/56684] Modified Julian Date of observation
22- 27 F6.3 mag mag [9.369/19.94] Observed magnitude in Filter
29- 33 F5.3 mag e_mag Uncertainty in mag
35- 44 A10 --- Source Facility used to obtain the photometry (2)
--------------------------------------------------------------------------------
Note (1): Filters are:
m2 = Swift/UVOT uvm2 band (λeff=2246Å);
w1 = Swift/UVOT uvw1 band (λeff=2600Å);
w2 = Swift/UVOT uvw2 band (λeff=1928Å);
BVRI/JHK = from SMARTS;
CCD BVRI = observations from the AAVSO.
Note (2): Facilities are defined as below:
AAVSO = American Association of Variable Star Observers;
SMARTS = Small & Moderate Aperture Research Telescope System;
Swift/UVOT = Swift/UltraViolet and Optical Telescope.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.3 d Dt1 [0.5/672] Time since discovery (G1)
9- 17 F9.3 d MJD1 Modified Julian Date corresponding to Dt1
19 A1 --- l_CR [<] Upper limit flag on CR
20- 24 F5.3 ct/s CR [0.003/5.89] Count Rate
26- 30 F5.3 ct/s E_CR ? Positive uncertainty in CR
32- 36 F5.3 ct/s e_CR ? Negative uncertainty in CR
38- 43 F6.3 d Dt2 ? Time since discovery for HR result (G1)
45- 53 F9.3 d MJD2 ? Modified Julian Date corresponding to Dt2
55- 59 F5.3 --- HR [0.2/2.19]? Hardness ratio (1)
61- 64 F4.2 --- E_HR ? Positive uncertainty in HR
66- 69 F4.2 --- e_HR ? Negative uncertainty in HR
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Note (1): HR=(0.5-10keV)/(0.3-0.5keV).
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Global notes:
Note (G1): Where the discovery date was 2012-03-26.397 (MJD=56012.897).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 17-Mar-2015