J/A+A/655/A90 SN 2020cxd multi-photometry (Yang+, 2021)
A low-energy explosion yields the underluminous Type IIP SN 2020cxd.
Yang S., Sollerman J., Strotjohann N.L., Schulze S., Lunnan R., Kool E.,
Fremling C., Perley D., Ofek E., Schweyer T., Bellm E.C., Kasliwal M.M.,
Masci F.J., Rigault M., Yang Y.
<Astron. Astrophys. 655, A90 (2021)>
=2021A&A...655A..90Y 2021A&A...655A..90Y (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry, ugriz ; Spectroscopy
Keywords: supernovae: general - galaxies: individual: NGC 6395
Abstract:
We present observations and analysis of SN 2020cxd, a low-luminosity
(LL), long-lived Type IIP supernova (SN). This object was a clear
outlier in the magnitude-limited SN sample recently presented by the
Zwicky Transient Facility (ZTF) Bright Transient Survey. We
demonstrate that SN 2020cxd is an additional member of the group of LL
SNe, and discuss the rarity of LL SNe in the context of the ZTF
survey, and how further studies of these faintest members of the
core-collapse (CC) SN family might help understand the underlying
initial mass function for stars that explode. We present optical light
curves (LCs) from the ZTF in the $gri$ bands and several epochs of
ultra-violet data from the Neil Gehrels Swift Observatory as well as a
sequence of optical spectra. We construct colour curves, a bolometric
LC, compare ejecta-velocity and black-body temperature evolutions for
LL SNe, as well as for typical Type II SNe. Furthermore, we adopt a
Monte Carlo code that fits semi-analytic models to the LC of SN
2020cxd, which allows the estimation of physical parameters. Using our
late-time nebular spectra, we also compare against SN II spectral
synthesis models from the literature to constrain the progenitor
properties of SN 2020cxd. The LCs of SN 2020cxd show great similarity
with those of LL SNe IIP, in luminosity, timescale and colours. Also
the spectral evolution of SN 2020cxd is that of a Type IIP SN. The
spectra show prominent and narrow P-Cygni lines, indicating low
expansion velocities. This is one of the faintest LL SNe observed,
with an absolute plateau magnitude of Mr=-14.5mag, and also
one with the longest plateau lengths, with a duration of 118 days.
Finally, the velocities measured from the nebular emission lines are
among the lowest ever seen in a SN, with intrinsic Full Width at Half
Maximum of 478km/s. The underluminous late-time exponential LC tail
indicates that the mass of 56Ni ejected during the explosion is much
smaller than the average of normal SNe IIP, we estimate
M56^Ni=0.003M+{sun+. The Monte Carlo fitting of the bolometric LC
suggests that the progenitor of SN 2020cxd had a radius of
R0=1.3x1013cm, kinetic energy of Ekin=4.3x1050erg, and ejecta
mass Mej=9.5M☉. From the bolometric LC, we estimate the total
radiated energy Erad=1.52x1048erg. Using our late-time nebular
spectra, we compare against SN II spectral synthesis models to
constrain the progenitor Zero-age Main-sequence mass and found it
likely to be ≲15M_☉+. SN 2020cxd is a LL Type IIP SN. The
inferred progenitor parameters and the features observed in the
nebular spectrum favour a low-energy, Ni-poor, iron CC SN from a low
mass ∼12M☉ red supergiant.
Description:
Photometric and spectroscopic data for SN 2020cxd.
Objects:
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RA (2000) DE Designation(s)
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17 26 29.26 +71 05 38.6 SN 2020cxd = SN 2020cxd
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ground.dat 81 89 Photometry of P48 P60 LT and NOT
swift.dat 88 6 Photometry of Swift UVOT
lt-0220.dat 30 432 Calibrated Spectrum of LT on 2020/02/20
p60-0220.dat 30 214 Calibrated Spectrum of P60 on 2020/02/20
p60-0225.dat 30 214 Calibrated Spectrum of P60 on 2020/02/25
p60-0522.dat 30 214 Calibrated Spectrum of P60 on 2020/05/22
lt-0625.dat 30 432 Calibrated Spectrum of LT on 2020/06/25
p60-0626.dat 30 214 Calibrated Spectrum of P60 on 2020/06/26
not-0701.dat 30 1705 Calibrated Spectrum of NOT on 2020/07/01
gemini.dat 30 1308 Calibrated Spectrum of Gemini on 2020/07/28
keck1.dat 30 5106 Calibrated Spectrum of Keck1 on 2020/10/19
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See also:
http://www.wiserep.org/object/14204 : WISeREP
Byte-by-byte Description of file: ground.dat
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Bytes Format Units Label Explanations
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1- 10 F10.2 d JD [2458896.0/2459131.37] Julian Date
12- 18 F7.2 d Phase [-1.52/232.94] Rest Frame Phase
20- 22 A3 --- Inst Instrument Name
23 A1 --- l_umag Upper limit flag on umag
24- 28 F5.2 mag umag ?=99 u band magnitude (1)
30- 34 F5.2 mag e_umag ?=99 Error of u band magnitude
35 A1 --- l_gmag Upper limit flag on gmag
36- 40 F5.2 mag gmag ?=99 g band magnitude (1)
42- 46 F5.2 mag e_gmag ?=99 Error of g band magnitude
47 A1 --- l_rmag Upper limit flag on rmag
48- 52 F5.2 mag rmag ?=99 r band magnitude (1)
54- 58 F5.2 mag e_rmag ?=99 Error of r band magnitude
59 A1 --- l_imag Upper limit flag on imag
60- 64 F5.2 mag imag ?=99 i band magnitude (1)
66- 70 F5.2 mag e_imag ?=99 Error of i band magnitude
72- 75 F4.1 mag zmag ?=99 z band magnitude
77- 81 F5.2 mag e_zmag ?=99 Error of z band magnitude
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Note (1): Measurements with magnitude error of 99 stands for upper limits.
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Byte-by-byte Description of file: swift.dat
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Bytes Format Units Label Explanations
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1- 10 F10.2 d JD [2458899.87/2459003.04] Julian Date
12- 17 F6.2 d Phase [2.33/105.1] Rest Frame Phase
18 A1 --- l_Vmag Upper limit flag on Vmag
19- 23 F5.2 mag Vmag V band magnitude (1)
25- 29 F5.2 mag e_Vmag ?=99 Error of V band magnitude
31- 35 F5.2 mag Bmag B band magnitude
37- 40 F4.2 mag e_Bmag Error of B band magnitude
41 A1 --- l_Umag Upper limit flag on Umag
42- 46 F5.2 mag Umag U band magnitude (1)
48- 52 F5.2 mag e_Umag ?=99 Error of U band magnitude
53 A1 --- l_UVW1 Upper limit flag on UVW1
54- 58 F5.2 mag UVW1 ?=99 UVW1 band magnitude (1)
60- 64 F5.2 mag e_UVW1 ?=99 Error of UVW1 band magnitude
65 A1 --- l_UVW2 Upper limit flag on UVW2
66- 70 F5.2 mag UVW2 ?=99 UVW2 band magnitude (1)
72- 76 F5.2 mag e_UVW2 ?=99 Error of UVW2 band magnitude
77 A1 --- l_UVM2 Upper limit flag on UVM2 (1)
78- 82 F5.2 mag UVM2 ?=99 UVM2 band magnitude
84- 88 F5.2 mag e_UVM2 ?=99 Error of UVM2 band magnitude
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Note (1): Measurements with magnitude error of 99 stands for upper limits.
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Byte-by-byte Description of file: gem*.dat keck1.dat lt*.dat not*.dat p60*.dat
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Bytes Format Units Label Explanations
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1- 7 F7.1 0.1nm lambda Wavelength
9- 30 E22.17 10mW/m2/nm Flux ?=0 Flux (erg/cm2/s/Å)
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Acknowledgements:
Sheng Yang, sheng.yang(at)astro.su.se
(End) Patricia Vannier [CDS] 22-Aug-2021