J/ApJ/902/139 Nebular spectroscopy of type IIb SN 2016gkg (Kuncarayakti+, 2020)
Direct evidence of two-component ejecta in supernova 2016gkg from nebular
spectroscopy.
Kuncarayakti H., Folatelli G., Maeda K., Dessart L., Jerkstrand A.,
Anderson J.P., Aoki K., Bersten M.C., Ferrari L., Galbany L., Garcia F.,
Gutierrez C.P., Hattori T., Kawabata K.S., Kravtsov T., Lyman J.D.,
Mattila S., F.O. E, Sanchez S.F., Van Dyk S.D.
<Astrophys. J., 902, 139 (2020)>
=2020ApJ...902..139K 2020ApJ...902..139K
ADC_Keywords: Spectra, optical; Supernovae
Keywords: Core-collapse supernovae
Abstract:
Spectral observations of the type-IIb supernova (SN) 2016gkg at
300-800 days are reported. The spectra show nebular characteristics,
revealing emission from the progenitor star's metal-rich core and
providing clues to the kinematics and physical conditions of the
explosion. The nebular spectra are dominated by emission lines of
[OI]λλ6300,6364 and [CaII]λλ7292,7324.
Other notable, albeit weaker, emission lines include MgI]
λ4571, [FeII]λ7155, OIλ7774, CaII triplet, and a
broad, boxy feature at the location of Hα. Unlike in other
stripped-envelope SNe, the [OI] doublet is clearly resolved due to the
presence of strong narrow components. The doublet shows an
unprecedented emission line profile consisting of at least three
components for each [OI]λ6300,6364 line: a broad component
(width ∼2000km/s), and a pair of narrow blue and red components (width
∼300km/s) mirrored against the rest velocity. The narrow component
appears also in other lines, and is conspicuous in [OI]. This
indicates the presence of multiple distinct kinematic components of
material at low and high velocities. The low-velocity components are
likely to be produced by a dense, slow-moving emitting region near the
center, while the broad components are emitted over a larger volume.
These observations suggest an asymmetric explosion, supporting the
idea of two-component ejecta that influence the resulting late-time
spectra and light curves. SN 2016gkg thus presents striking evidence
for significant asymmetry in a standard-energy SN explosion. The
presence of material at low velocity, which is not predicted in 1D
simulations, emphasizes the importance of multidimensional explosion
modeling of SNe.
Description:
SN 2016gkg was observed with the Gemini South telescope and the GMOS-S
instrument, on 2017 August 20 and 26. Another GMOS-S longslit
observation was performed on 2018 November 10 (+764d).
On 2017 November 30, the field of SN 2016gkg was observed using the
MUSE instrument at the ESO Very Large Telescope.
SN 2016gkg was also observed using FOCAS at the Subaru telescope on
2018 January 1 (+451d).
Objects:
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RA (ICRS) DE Designation(s)
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01 34 14.40 -29 26 24.2 SN 2016gkg = ATLAS 16cvu
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 40 10087 Nebular spectra of SN 2016gkg
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See also:
VIII/73 : HI Parkes All Sky Survey Catalogue (HIPASS) (Meyer+, 2004)
J/MNRAS/372/1315 : UBVRI photometry of SN 2004et (Sahu+, 2006)
J/MNRAS/416/3138 : SN 2009jf light curves (Valenti+, 2011)
J/A+A/559/A114 : Updated O3N2 and N2 abundance indicators (Marino+, 2013)
J/ApJ/785/37 : Type Ic SN 2010mb optical photometry (Ben-Ami+, 2014)
J/MNRAS/442/844 : BVRI light curves of type II-P supernovae (Faran+, 2014)
J/A+A/580/A142 : SN 2011dh. The first two years (Ergon+, 2015)
J/A+A/573/A12 : SN1993J spectra 100-500d post-explosion (Jerkstrand+, 2015)
J/ApJ/854/L14 : Photometry and spectra of SN 2017dio (Kuncarayakti+, 2018)
J/ApJ/885/43 : UBVRI & ugriz phot. of supernova SN 2017gmr (Andrews+, 2019)
J/ApJ/873/L3 : NUV to NIR photometry of type IIP ASASSN-16at (Bose+, 2019)
J/AJ/159/167 : AMUSING++ nearby galaxy compilation. I. (Lopez-Coba+, 2020)
Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Inst Instrument identifier (1)
7- 9 I3 --- Phase [320/764] Days after maximum
11- 26 F16.11 0.1nm lambda [4458.68/9303.71] Wavelength
in Angstrom units
28- 40 F13.7 10-20cW/m2/nm RFlux [-798.2/16259.3] Relative flux;
in 10-20erg/s/cm2/Å units
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Note (1): Instrument as follows:
MUSE = MUSE instrument (R∼2200) at the ESO Very Large Telescope
(3681 occurrences)
FOCAS = FOCAS instrument (R∼700) at the Subaru telescope (3210 occurrences)
GMOS = the GMOS-S instrument (R∼700) at the Gemini South telescope
(3196 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Apr-2022