J/A+A/646/A119 M31 luminous red nova AT 2019zhd photometry (Pastorello+, 2021)
Forbidden hugs in pandemic times.
I. Luminous red nova AT 2019zhd, a new merger in M 31.
Pastorello A., Fraser M., Valerin G., Reguitti A., Itagaki K., Ochner P.,
Williams S.C., Jones D., Munday J., Smartt S.J., Smith K.W., Srivastav S.,
Elias-Rosa N., Kankare E., Karamehmetoglu E., Lundqvist P., Mazzali P.A.,
Munari U., Stritzinger M., Tomasella L., Anderson J.P., Chambers K.C.,
Rest A.
<Astron. Astrophys. 646, A119 (2021)>
=2021A&A...646A.119P 2021A&A...646A.119P (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Novae ; Photometry, UBV ; Photometry, ugriz
Keywords: binaries: close - stars: winds, outflows -
stars: individual: AT 2019zhd - stars: individual: M31-LRN2015 -
stars: individual: M31-RV - stars: individual: V838 Mon
Abstract:
We present the follow-up campaign of the luminous red nova (LRN)
AT 2019zhd, the third event of this class observed in M 31. The object
was followed by several sky surveys for about five months before the
outburst, during which it showed a slow luminosity rise. In this
phase, the absolute magnitude ranged from Mr=-2.8±0.2mag to
Mr=-5.6±0.1mag. Then, over a four to five day period, AT 2019zhd
experienced a major brightening, reaching a peak of
Mr=-9.61±0.08mag and an optical luminosity of 1.4x1039erg/s.
After a fast decline, the light curve settled onto a short-duration
plateau in the red bands. Although less pronounced, this feature is
reminiscent of the second red maximum observed in other LRNe. This
phase was followed by a rapid linear decline in all bands. At maximum,
the spectra show a blue continuum with prominent Balmer emission
lines. The post-maximum spectra show a much redder continuum,
resembling that of an intermediate-type star. In this phase, Halpha
becomes very weak, Hbeta is no longer detectable, and a forest of
narrow absorption metal lines now dominate the spectrum. The latest
spectra, obtained during the post-plateau decline, show a very red
continuum (Teff∼3000K) with broad molecular bands of TiO, similar to
those of M-type stars. The long-lasting, slow photometric rise
observed before the peak resembles that of LRN V1309 Sco, which was
interpreted as the signature of the common-envelope ejection. The
subsequent outburst is likely due to the gas outflow following a
stellar merging event. The inspection of archival HST images taken 22
years before the LRN discovery reveals a faint red source
(MF555W=0.21±0.14mag, with F555W-F814W=2.96±0.12mag) at the
position of AT 2019zhd, which is the most likely quiescent precursor.
The source is consistent with expectations for a binary system
including a predominant M5-type star.
Description:
Johnson-Bessell B,V photometry of AT 2019zhd (Vega magnitude system)
and associated errors.
Objects:
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RA (2000) DE Designation(s)
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00 40 37.90 +40 34 52.8 AT 2019zhd = ZTF19adakuot
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 54 35 Broadband Johnson-Bessell B,V photometry of
AT 2019zhd (Vega magnitude system) and
associated errors
table2.dat 119 142 Broadband Sloan ugriz, PS-w and ATLAS-o
photometry of AT 2019zhd (AB magnitude system)
and associated errors
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See also:
J/A+A/647/A93 : AT 2020hat and AT 2020kog light curves (Pastorello+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Date Date of the observation (yyyy-mm-dd)
13- 20 F8.2 d MJD Modified Julian Date
23 A1 --- l_Bmag Detection limit symbol
24- 29 F6.3 mag Bmag ?=- Johnson-Bessell B-band magnitude (Vega)
32- 36 F5.3 mag e_Bmag ?=- B-band magnitude error
39- 44 F6.3 mag Vmag ?=- Johnson-Bessell V-band magnitude (Vega)
47- 51 F5.3 mag e_Vmag ?=- V-band magnitude error
54 A1 --- Inst Instrumental configuration code (1)
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Note (1): Instrumental configuration code as follows:
0 = 2.0 m Faulkees North Telescope + fa05 camera (Hawaii Isl., USA)
1 = CBAT Transient Object Followup Reports
http://www.cbat.eps.harvard.edu/unconf/followups/J00403785+4034529.html
2 = AAVSO Observations from the AAVSO International Database
(Kafka 2000, https://www.aavso.org)
3 = ANS Collaboration telescopes ID 310 and 2202
(Munari et al. 2020ATel13484....1M 2020ATel13484....1M)
4 = 1.82 m Copernico Telescope + AFOSC (Cima Ekar, Asiago, Italy)
5 = 67/92 cm Schmidt Telescope + Moravian G4-16000LC + KAF-16803 CCD CCD
(Cima Ekar, Asiago, Italy)
6 = 2.0 m Liverpool Telescope (LT) + IO:O (La Palma, Canary Islands, Spain)
7 = 2.56 m Nordic Optical Telescope (NOT) + ALFOSC (La Palma, Canary Islands,
Spain)
8 = 0.61 m Planewave CDK24 telescope + Apogee CG-16M Camera (Burke-Gaffney
Observatory, Saint Marys University, Canada)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Date Date of the observation (yyyy-mm-dd)
13- 20 F8.2 d MJD Modified Julian Date
23- 28 F6.3 mag umag ?=- Sloan u-band magnitude (AB)
31- 35 F5.3 mag e_umag ?=- u-band magnitude error
38 A1 --- l_gmag Detection limit symbol
39- 44 F6.3 mag gmag ?=- Sloan g-band magnitude (AB)
47- 51 F5.3 mag e_gmag ?=- g-band magnitude error
54 A1 --- l_rmag Detection limit symbol
55- 60 F6.3 mag rmag ?=- Sloan r-band magnitude (AB)
63- 67 F5.3 mag e_rmag ?=- r-band magnitude error
70 A1 --- l_imag Detection limit symbol
71- 76 F6.3 mag imag ?=- Sloan i-band magnitude (AB)
79- 83 F5.3 mag e_imag ?=- i-band magnitude error
86- 91 F6.3 mag zmag ?=- Sloan z-band magnitude (AB)
94- 98 F5.3 mag e_zmag ?=- z-band magnitude error
101 A1 --- l_womag Detection limit symbol
102-107 F6.3 mag womag ?=- PS-w or ATLAS-o magnitude (AB)
110-114 F5.3 mag e_womag ?=- PS-w or ATLAs-o magnitude error
117-118 I2 --- Inst Instrumental configuration code (1)
119 A1 --- Notes Letter code for additional notes (2)
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Note (1): Instrumental configuration code as follows:
1 = 35 cm F/11 telescope + KAF-1001E CCD (Itagaki Astronomical Observatory,
Yamagata, Japan)
2 = 2.0 m Liverpool Telescope (LT) + IO:O (La Palma, Canary Islands, Spain)
3 = 1.8 m Pan-STARRS Telescopes + GPC cameras (Haleakala, Hawaii Islands, USA)
4 = 1.2 m S. Oschin Telescope + ZTF-Cam (Mt. Palomar, USA)
5 = 0.5 m ATLAS Telescope + ACAM2 (Mauna Loa, Hawaii Islands, USA)
6 = 0.5 m ATLAS Telescope + ACAM1 (Haleakala, Hawaii Islands, USA)
7 = 2.0m Faulkees North Telescope + fa05 camera (Hawaii Isl., USA)
8 = ASAS-SN 4x0.16 m Brutus Telescope + FLI ProLine PL230 CCD (LCOGT -
Haleakala, Hawaii Islands, USA; see Kochanek et al. 2017PASP..129j4502K 2017PASP..129j4502K)
9 = B,V,R,I Johnson-Bessell-Cousins observations from AAVSO, TOCP and ANS
collaboration, converted in Sloan bands following the prescriptions of
Jordi et al. (2006A&A...460..339J 2006A&A...460..339J)
10 = 1.82 m Copernico Telescope + AFOSC (Cima Ekar, Asiago, Italy)
11 = 67/92 cm Schmidt Telescope + Moravian G4-16000LC + KAF-16803 CCD CCD
(Cima Ekar, Asiago, Italy)
12 = 2.56 m Nordic Optical Telescope (NOT) + ALFOSC (La Palma, Canary Islands,
Spain)
13 = 2.56 m Nordic Optical Telescope (NOT) + StanCam (La Palma, Canary Islands,
Spain)
Note (2): Letter code for additional notes as follows:
A = Pan-STARRS w-band data
B = ATLAS-c band data, converted to Sloan g (Tonry et al. 2018PASP..130f4505T 2018PASP..130f4505T)
C = Unfiltered pointing data, scaled to Sloan-r photometry
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Acknowledgements:
Andrea Pastorello, andrea.pastorello(at)inaf.it
References:
Pastorello et al., Paper II 2021A&A...647A..93P 2021A&A...647A..93P, Cat. J/A+A/647/A93
(End) Patricia Vannier [CDS] 18-Dec-2020