J/ApJ/881/87 9 epochs spectroscopy of type I supernova SN 201iet (Gomez+, 2019)
SN 2016iet: the pulsational or pair instability explosion of a low-metallicity
massive CO core embedded in a dense hydrogen-poor circumstellar medium.
Gomez+, Gomez S., Berger E., Nicholl M., Blanchard P.K., Villar V.A.,
Patton L., Chornock R., Leja J., Hosseinzadeh G., Cowperthwaite P.S.
<Astrophys. J., 881, 87 (2019)>
=2019ApJ...881...87G 2019ApJ...881...87G
ADC_Keywords: Supernovae; Spectra, optical
Keywords: supernovae: general ; supernovae: individual (SN2016iet)
Abstract:
We present optical photometry and spectroscopy of SN2016iet
(=Gaia16bvd=PS17brq), an unprecedented Type I supernova (SNI) at
z=0.0676 with no obvious analog in the existing literature. SN2016iet
exhibits a peculiar light curve, with two roughly equal brightness
peaks (~-19mag) separated by about 100 days, and a subsequent slow
decline by about 5mag in 650 rest-frame days. The spectra are
dominated by strong emission lines of calcium and oxygen, with a width
of only 3400km/s, superposed on a strong blue continuum in the first
year. There is no clear evidence for hydrogen or helium associated
with the SN at any phase. The nebular spectra exhibit a ratio of
LCaII/LOI∼4, much larger than for core-collapse SNe and TypeI
superluminous SNe. We model the light curves with several potential
energy sources: radioactive decay, a central engine, and
ejecta-circumstellar medium (CSM) interaction. Regardless of the
model, the inferred progenitor mass near the end of its life (i.e.,
the CO core mass) is ≳55M☉ and potentially up to 120M☉,
clearly placing the event in the regime of pulsational pair
instability supernovae (PPISNe) or pair instability supernovae
(PISNe). The models of CSM interaction provide the most consistent
explanation for the light curves and spectra, and require a CSM mass
of ∼35M☉ ejected in the final decade before explosion. We further
find that SN2016iet is located at an unusually large projected offset
(16.5kpc, 4.3 effective radii) from its low-metallicity dwarf host
galaxy (Z∼0.1Z☉, L∼0.02L*, M∼108.5M☉), supporting the
interpretation of a PPISN/PISN explosion. In our final spectrum at a
phase of about 770 rest-frame days we detect weak and narrow Hα
emission at the location of the SN, corresponding to a star formation
rate of ∼3x10-4M☉/yr, which is likely due to a dim underlying
galaxy host or an HII region. Despite the overall consistency of the
SN and its unusual environment with PPISNe and PISNe, we find that the
inferred properties of SN2016iet challenge existing models of such
events.
Description:
We obtained nine epochs of low-resolution optical spectroscopy at
phases of 132-772days. We used the Inamori-Magellan Areal Camera and
Spectrograph (IMACS) and the Low Dispersion Survey Spectrograph 3
(LDSS3c) spectrographs on the Magellan telescopes, the Blue Channel
and Binospec spectrographs on the Multi Mirror Telescope (MMT), the
Gemini-North Multi-Object Spectrograph (GMOS), and the Ohio State
Multi-Object Spectrograph (OSMOS) on the 2.4m Hiltner Telescope at
Michigan-Dartmouth-MIT (MDM) Observatory.
Objects:
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RA (2000) DE Designation(s)
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12 32 33.23 +27 07 15.5 SN 2016iet = Gaia 16bvd
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig4a.dat 50 4085 Optical spectra of SN 2016iet at MJD=57873.0
(Phase 132)
fig4b.dat 50 2654 Optical spectra of SN 2016iet at MJD=57895.0
(Phase 153)
fig4c.dat 50 4072 Optical spectra of SN 2016iet at MJD=57921.0
(Phase 177)
fig4d.dat 50 2708 Optical spectra of SN 2016iet at MJD=57932.0
(Phase 187)
fig4e.dat 50 2699 Optical spectra of SN 2016iet at MJD=58082.0
(Phase 328)
fig4f.dat 50 2452 Optical spectra of SN 2016iet at MJD=58144.0
(Phase 386)
fig4g.dat 50 4096 Optical spectra of SN 2016iet at MJD=58158.5
(Phase 399)
fig4h.dat 50 3320 Optical spectra of SN 2016iet at MJD=58194.0
(Phase 433)
fig4i.dat 50 5770 Optical spectra of SN 2016iet at MJD=58556.582292
(Phase 772)
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See also:
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/ApJ/742/89 : Relations between spectra and colors of SNe Ia (Foley+, 2011)
J/ApJ/745/74 : Pre-maximum spectra of type Ia SNe (Folatelli+, 2012)
J/ApJ/759/107 : Core-collapse SNe and host galaxies (Kelly+, 2012)
J/ApJ/793/38 : Palomar Transient Factory photometric obs. (Arcavi+, 2014)
J/ApJ/785/37 : Type Ic SN 2010mb optical photometry (Ben-Ami+, 2014)
J/ApJ/794/23 : Pan-STARRS1 transients optical photometry (Drout+, 2014)
J/A+A/573/A2 : SN 2012Z spectra (Stritzinger+, 2015)
J/A+A/573/A12 : SN1993J spectr 100to500 days post-explosion (Jerkstrand+, 2015)
J/ApJ/832/108 : Spectral properties of Type Ic & Ic-bl SNe (Modjaz+, 2016)
J/A+A/602/A93 : SN Type Ibn OGLE-2014-SN-131 lightcurves (Karamehmetoglu+,2017)
J/ApJ/836/60 : Bgri light curves of PTF11kmb and PTF12bho (Lunnan+, 2017)
J/ApJ/835/58 : PTF 12dam & iPTF 13dcc follow-up (Vreeswijk+, 2017)
J/ApJ/853/62 : Optical and NIR spectra and LCs of SN2016ija (Tartaglia+, 2018)
J/ApJ/854/L14 : Photometry and spectra of SN 2017dio (Kuncarayakti+, 2018)
J/ApJ/863/109 : Follow-up optical obs. of the SNIc SN2014L (Zhang+, 2018)
Byte-by-byte Description of file: fig4*.dat
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Bytes Format Units Label Explanations
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1- 24 E24.18 0.1nm wave Spectrum wavelength, Angstroms
26- 50 E25.18 10mW/m2/nm flux Spectrum flux, erg/cm2/s/Å
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 24-Dec-2020