J/ApJ/934/102 Follow-up LCO photometry & spectra of SN 2016dsg (Dong+, 2022)
SN 2016dsg: a thermonuclear explosion involving a thick Helium shell.
Dong Y., Valenti S., Polin A., Boyle A., Flors A., Vogl C.,
Kerzendorf W.E., Sand D.J., Jha S.W., Wyrzykowski L., Bostroem K.A.,
Pearson J., McCully C., Andrews J.E., Benetti S., Blondin S., Galbany L.,
Gromadzki M., Hosseinzadeh G., Howell D.A., Inserra C., Jencson J.E.,
Lundquist M., Lyman J.D., Magee M., Maguire K., Meza N., Srivastav S.,
Taubenberger S., Terwel J.H., Wyatt S., Young D.R.
<Astrophys. J., 934, 102 (2022)>
=2022ApJ...934..102D 2022ApJ...934..102D
ADC_Keywords: Supernovae; Photometry, VRI; Spectra, optical; Spectra, infrared
Keywords: Supernovae ; Type Ia supernovae
Abstract:
A thermonuclear explosion triggered by a He-shell detonation on a
carbon-oxygen white-dwarf core has been predicted to have strong UV
line blanketing at early times due to the iron-group elements produced
during He-shell burning. We present the photometric and spectroscopic
observations of SN 2016dsg, a subluminous peculiar Type I supernova
consistent with a thermonuclear explosion involving a thick He shell.
With a redshift of 0.04, the i-band peak absolute magnitude is derived
to be around -17.5. The object is located far away from its host, an
early-type galaxy, suggesting it originated from an old stellar
population. The spectra collected after the peak are unusually red,
show strong UV line blanketing and weak OIλ7773 absorption
lines, and do not evolve significantly over 30 days. An absorption
line around 9700-10500Å is detected in the near-infrared spectrum
and is likely from the unburnt He in the ejecta. The spectroscopic
evolution is consistent with the thermonuclear explosion models for a
sub-Chandrasekhar-mass white dwarf with a thick He shell, while the
photometric evolution is not well described by existing models.
Description:
SN 2016dsg was discovered by the Gaia Photometric Alert System
on 2016 February 21 (JD 2457440.02).
The follow-up observations started from 2016 February 26. Photometric
data were obtained through Global Supernova Project with the Las
Cumbres Observatory (LCO). See Table A1.
Two optical spectra and one near-infrared (NIR) spectrum were obtained
by the PESSTO collaboration (Smartt+ 2015, J/A+A/579/A40). The optical
spectra were taken with the ESO Faint Object Spectrograph and Camera
(v.2) (EFOSC2) on the 3.6m New Technology Telescope (NTT). The NIR
spectrum was taken with the Son of ISAAC infrared spectrograph and
imaging camera (SofI) on the NTT. In addition, five optical spectra
were collected with the Southern African Large Telescope (SALT) using
the Robert Stobie Spectrograph (RSS). One low-dispersion optical
spectrum was obtained on 2016-Feb-27 by the FLOYDS spectrograph on FTS
(2m telescope in Australia). However, this spectrum had a low
signal-to-noise ratio, so we did not use it for analysis. All the
spectroscopic observations are listed in Table 1.
Objects:
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RA (ICRS) DE Designation(s)
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06 07 08.18 -45 10 52.2 SN 2016dsg = Gaia 16afe
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 160 9 Spectroscopic observations of SN 2016dsg
tablea1.dat 68 177 Optical photometry of SN 2016dsg
fits/* . 9 The nine spectra observed in FITS format
(Data behind Figure 4)
sp/* . 15 The original spectra and flux-calibrated
spectra used in the analysis in ASCII format
(Data behind Figure 4)
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See also:
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
J/A+A/523/A48 : Gaia photometry (Jordi+, 2010)
J/MNRAS/438/L101 : First month on SN 2013ej (Valenti+, 2014)
J/A+A/579/A40 : PESSTO catalog (Smartt+, 2015)
J/MNRAS/459/3939 : Type II supernova light curves (Valenti+, 2016)
J/A+A/630/A76 : SN2016hnk photometry and spectroscopy (Galbany+, 2019)
J/ApJ/905/58 : The local universe. I. Ca-rich gap transients (De+, 2020)
J/ApJ/896/165 : Optical light curves of SN 2016hnk (Jacobson-Galan+, 2020)
J/ApJ/898/56 : UVOT, ZTF gri LCs & sp. of the SN Ia 2019yvq (Miller+, 2020)
J/A+A/652/A76 : Gaia Photometric Science Alerts (Hodgkin+, 2021)
J/ApJ/914/50 : Opt. phot. & GMOS & NIRES sp. of SN2019yvq (Tucker+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "Y/M/D" Date UT date of observation
12- 21 F10.2 d JD Julian date of observation
23- 26 F4.1 d Phase [4.7/54.2] Phase with respect to the discovery
date (2016 February 21 = JD2457440.02)
28- 31 A4 --- Tel Telescope (NTT, FTS or SALT)
33- 38 A6 --- Inst Instrument
40- 46 A7 --- Res Resolution λ/Δλ
48- 57 A10 0.1nm lambda Wavelength range in Å
59- 92 A34 --- FileName1 Name of the original spectrum
in subdirectory "sp"; column added by CDS
94-127 A34 --- FileName2 Name of the flux-calibrated spectrum
in subdirectory "sp"; column added by CDS
129-160 A32 --- FileName3 Name of the FITS spectrum
in subdirectory "fits"; column added by CDS
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 yr Obs.Y [2016] Observation date, year
6- 7 I2 "month" Obs.M Observation date, month in year
9- 10 I2 d Obs.D Observation date, day in month
12- 24 F13.5 d JD Julian Date of observation
26- 44 F19.16 d Phase [4.69/58.5] Days since the discovery date
(JD=2457440.02)
46- 52 F7.4 mag omag [18.4/22.2] Apparent Magnitude in Filter
54- 59 F6.4 mag e_omag [0.05/0.5] Error in omag
61- 61 A1 --- Filt Filter (V, g, r or i)
63- 68 A6 --- Tel Telescope used to take the data (1)
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Note (1): Las Cumbres Observatory (LCO) telescopes as follows:
CPT 1m = South African Astronomical Observatory 1m telescope (32 occurrences)
COJ 1m = Siding Spring Observatory 1-m telescope (19 occurrences)
COJ 2m = Siding Spring Observatory 2-m telescope (2 occurrences)
LSC 1m = Cerro Tololo Interamerican Observatory 1m telescope (124 occurrences)
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 18 A18 0.1m lambda Rest wavelength in Angstroms
20- 42 A23 mW/m2 Flux Flux in erg/s/cm2
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Jul-2024