J/MNRAS/493/1761 SN 2016gsd: an unusually luminous supernova (Reynolds+, 2020)
SN 2016gsd: an unusually luminous and linear Type II supernova with high
velocities.
Reynolds T.M., Fraser M., Mattila S., Ergon M., Dessart L., Lundqvist P.,
Dong S., Elias-Rosa N., Galbany L., Gutierrez C.P., Kangas T., Kankare E.,
Kotak R., Kuncarayakti H., Pastorello A., Rodriguez O., Smartt S.J.,
Stritzinger M., Tomasella L., Chen P., Harmanen J., Hosseinzadeh G.,
Howell D.A., Inserra C., Nicholl M., Nielsen M., Smith K., Somero A.,
Tronsgaard R., Young D.R.
<Mon. Not. R. Astron. Soc., 493, 1761-1781 (2020)>
=2020MNRAS.493.1761R 2020MNRAS.493.1761R (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Photometry, UBVRI ; Photometry, ugriz ;
Photometry, infrared
Keywords: techniques: imaging spectroscopy - supernovae:general -
supernovae: individual: SN 2016gsd
Abstract:
We present observations of the unusually luminous Type II supernova
(SN) 2016gsd. With a peak absolute magnitude of V=-19.95±0.08, this
object is one of the brightest Type II SNe, and lies in the gap of
magnitudes between the majority of Type II SNe and the superluminous
SNe. Its light curve shows little evidence of the expected drop from
the optically thick phase to the radioactively powered tail. The
velocities derived from the absorption in Hα are also unusually
high with the blue edge tracing the fastest moving gas initially at
20000km/s, and then declining approximately linearly to 15000km/s over
∼100d. The dwarf host galaxy of the SN indicates a low-metallicity
progenitor which may also contribute to the weakness of the metal
lines in its spectra. We examine SN 2016gsd with reference to
similarly luminous, linear Type II SNe such as SNe 1979C and 1998S,
and discuss the interpretation of its observational characteristics.
We compare the observations with a model produced by the JEKYLL code
and find that a massive star with a depleted and inflated hydrogen
envelope struggles to reproduce the high luminosity and extreme
linearity of SN 2016gsd. Instead, we suggest that the influence of
interaction between the SN ejecta and circumstellar material can
explain the majority of the observed properties of the SN. The high
velocities and strong Hα absorption present throughout the
evolution of the SN may imply a circumstellar medium configured in an
asymmetric geometry.
Description:
Optical imaging of SN 2016gsd was obtained as part of the Las Cumbres
Observatory (LCO; see Brown et al. 2013PASP..125.1031B 2013PASP..125.1031B) SN key project
with their network of 1.0m telescopes, equipped with Sinistro cameras;
with the 2.56m Nordic Optical Telescope (NOT2), using the ALFOSC
camera; with the 3.6m New Technology Telescope (NTT) equipped with the
EFOSC2 camera; and with the 1.82m Copernico Telescope using AFOSC.
Magnitudes for 20 field stars used for the calibration are given in
Table A1. The optical magnitudes of SN 2016gsd are listed in Tables A2
and A3.
NIR imaging of SN 2016gsd was performed with the NOT using the NOTCam
instrument and with the NTT using the SOFI instrument. The NIR SN
magnitudes obtained are reported in Table A4.
A log of spectroscopic observations of SN 2016gsd is reported in Table
A5.
Objects:
---------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------
02 40 34.43 +19 16 59.9 SN 2016gsd = AT 2016gsd
---------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 131 20 Magnitudes for the calibration stars shown in
Fig. 1.
tablea2.dat 86 38 Photometry of SN 2016gsd in the UBVRI bands
tablea3.dat 86 40 Photometry of SN 2016gsd in the ugriz bands
tablea4.dat 66 5 Photometry of SN 2016gsd in the JHK bands
tablea5.dat 55 11 Log of spectroscopic observations
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID [1/20] Star internal identifier
4- 11 F8.5 deg RAdeg Right ascension (J2000)
13- 20 F8.5 deg DEdeg Declination (J2000)
22- 26 F5.2 mag Umag ? U-band magnitude from the SCUSS survey (G1)
28- 31 F4.2 mag e_Umag ? Error on Umag
33- 37 F5.2 mag Bmag B-band magnitude converted from Pan-STARRS1 (G1)
39- 42 F4.2 mag e_Bmag Error on Bmag
44- 48 F5.2 mag Vmag V-band magnitude converted from Pan-STARRS1 (G1)
50- 53 F4.2 mag e_Vmag Error on Vmag
55- 59 F5.2 mag Rmag R-band magnitude converted from Pan-STARRS1 (G1)
61- 64 F4.2 mag e_Rmag Error on Rmag
66- 70 F5.2 mag Imag I-band magnitude converted from Pan-STARRS1 (G1)
72- 75 F4.2 mag e_Imag Error on Imag
77- 81 F5.2 mag umag ? SDSS u-band magnitude (G2)
83- 87 F5.3 mag e_umag ? Error on umag
89- 93 F5.2 mag gmag Sloan g-band magnitude (G2)
95- 98 F4.2 mag e_gmag Error on gmag
100-104 F5.2 mag rmag Sloan r-band magnitude (G2)
106-109 F4.2 mag e_rmag Error on rmag
111-115 F5.2 mag imag Sloan i-band magnitude (G2)
117-120 F4.2 mag e_imag Error on imag
122-126 F5.2 mag zmag Sloan z-band magnitude (G2)
128-131 F4.2 mag e_zmag Error on zmag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.1 d Phase Phase relative to the explosion epoch
(MJD=57648)
7- 16 A10 "Y:M:D" Date Date of observation
18- 24 F7.1 d MJD Epoch of the observation
26- 31 A6 --- Tel Telescope used for the observation
33- 37 F5.2 mag Umag ? U-band magnitude (G1)
39- 42 F4.2 mag e_Umag ? Error on Umag
44- 48 F5.2 mag Bmag ? B-band magnitude (G1)
50- 53 F4.2 mag e_Bmag ? Error on Bmag
55- 59 F5.2 mag Vmag V-band magnitude (G1)
61- 64 F4.2 mag e_Vmag Error on Vmag
66- 70 F5.2 mag Rmag ? R-band magnitude (G1)
72- 75 F4.2 mag e_Rmag ? Error on Rmag
77- 81 F5.2 mag Imag ? I-band magnitude (G1)
83- 86 F4.2 mag e_Imag ? Error on Imag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.1 d Phase Phase relative to the explosion epoch
(MJD=57648)
7- 16 A10 "Y:M:D" Date Date of observation
18- 24 F7.1 d MJD Epoch of the observation
26- 31 A6 --- Tel Telescope used for the observation
33- 37 F5.2 mag umag ? u-band magnitude (G2)
39- 42 F4.2 mag e_umag ? Error on umag
44- 48 F5.2 mag gmag ? g-band magnitude (G2)
50- 53 F4.2 mag e_gmag ? Error on gmag
55- 59 F5.2 mag rmag ? r-band magnitude (G2)
61- 64 F4.2 mag e_rmag ? Error on rmag
66- 70 F5.2 mag imag ? i-band magnitude (G2)
72- 75 F4.2 mag e_imag ? Error on imag
77- 81 F5.2 mag zmag ? z-band magnitude (G2)
83- 86 F4.2 mag e_zmag ? Error on zmag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.1 d Phase Phase relative to the explosion epoch
(MJD=57648)
7- 16 A10 "Y:M:D" Date Date of observation
18- 24 F7.1 d MJD Epoch of the observation
26- 31 A6 --- Inst Instrument used for the observation
33- 37 F5.2 mag Jmag ? J-band magnitude in the Vega system
39- 42 F4.2 mag e_Jmag ? Error on Jmag
44- 48 F5.2 mag Hmag ? H-band magnitude in the Vega system
50- 53 F4.2 mag e_Hmag ? Error on Hmag
55 A1 --- l_Kmag Limit flag on Kmag
57- 61 F5.2 mag Kmag ? K-band magnitude in the Vega system
63- 66 F4.2 mag e_Kmag ? Error on Kmag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.1 d Phase Phase relative to the explosion epoch
(MJD=57648)
7- 16 A10 "Y:M:D" Date Date of observation
18- 24 F7.1 d MJD Epoch of the observation
26- 30 A5 --- Tel Telescope used for the observation
32- 37 A6 --- Inst Instrument used for the observation
39- 44 A6 --- Grism Grism
46- 55 A10 0.1nm Range Wavelength range
--------------------------------------------------------------------------------
Global Notes:
Note (G1): UBVRI band magnitudes are in the Vega system
Note (G2): ugriz band magnitudes are in the AB system
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 14-Apr-2023