J/ApJ/900/140 CSP-II: sp. obs. of the 03fg-like SN Ia LSQ14fmg (Hsiao+, 2020)
Carnegie Supernova Project II: the slowest rising Type Ia supernova LSQ14fmg and
clues to the origin of super-Chandrasekhar/03fg-like events.
Hsiao E.Y., Hoeflich P., Ashall C., Lu J., Contreras C., Burns C.R.,
Phillips M.M., Galbany L., Anderson J.P., Baltay C., Baron E., Castellon S.,
Davis S., Freedman W.L., Gall C., Gonzalez C., Graham M.L., Hamuy M.,
Holoien T.W.-S., Karamehmetoglu E., Krisciunas K., Kumar S.,
Kuncarayakti H., Morrell N., Moriya T.J., Nugent P.E., Perlmutter S.,
Persson S.E., Piro A.L., Rabinowitz D., Roth M., Shahbandeh M.,
Shappee B.J., Stritzinger M.D., Suntzeff N.B., Taddia F., Uddin S.A.
<Astrophys. J., 900, 140 (2020)>
=2020ApJ...900..140H 2020ApJ...900..140H
ADC_Keywords: Supernovae; Spectra, optical; Photometry, UBVRI
Keywords: Type Ia supernovae ; Asymptotic giant branch stars ; Stellar winds
Abstract:
The Type Ia supernova (SN Ia) LSQ14fmg exhibits exaggerated properties
that may help to reveal the origin of the "super-Chandrasekhar" (or
03fg-like) group. The optical spectrum is typical of a 03fg-like SNIa,
but the light curves are unlike those of any SNe Ia observed. The
light curves of LSQ14fmg rise extremely slowly. At -23 rest-frame days
relative to B-band maximum, LSQ14fmg is already brighter than
MV=-19mag before host extinction correction. The observed color
curves show a flat evolution from the earliest observation to
approximately 1 week after maximum. The near-infrared light curves
peak brighter than -20.5mag in the J and H bands, far more luminous
than any 03fg-like SNe Ia with near-infrared observations. At 1 month
past maximum, the optical light curves decline rapidly. The early,
slow rise and flat color evolution are interpreted to result from an
additional excess flux from a power source other than the radioactive
decay of the synthesized 56Ni. The excess flux matches the interaction
with a typical superwind of an asymptotic giant branch (AGB) star in
density structure, mass-loss rate, and duration. The rapid decline
starting at around 1 month past B-band maximum may be an indication of
rapid cooling by active carbon monoxide (CO) formation, which requires
a low-temperature and high-density environment. These peculiarities
point to an AGB progenitor near the end of its evolution and the core
degenerate scenario as the likely explosion mechanism for LSQ14fmg.
Description:
The object LSQ14fmg was discovered by the La Silla-QUEST Low Redshift
Supernova Survey (LSQ; Baltay+ 2013PASP..125..683B 2013PASP..125..683B) using an image
taken on 2014 September 21.03 UT.
A classification spectrum was taken on 2014 September 24.95 UT with
the Andalucia Faint Object Spectrograph and Camera (ALFOSC) on the
Nordic Optical Telescope (NOT).
LSQ14fmg was then followed up by CSP-II as part of the "Cosmology"
sample (see Phillips+ 2019PASP..131a4001P 2019PASP..131a4001P) in the optical BVri bands
with the e2v CCD on the Swope Telescope and in the NIR YJH bands with
RetroCam on the du Pont Telescope. The field of LSQ14fmg was also
monitored by the ESO 1m Schmidt telescope and the Quest camera of LSQ
in the broad gr filter with an approximately 2 day cadence until
around maximum light.
After the first classification spectrum was taken with NOT+ALFOSC, two
additional follow-up spectra were also obtained with the NOT, creating
a time series that spans approximately 2.5 weeks.
Objects:
--------------------------------------------------
RA (ICRS) DE Designation(s)
--------------------------------------------------
22 16 46.10 +15 21 14.1 LSQ14fmg = LSQ 14fmg
--------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 60 43 Swope+e2v photometry of LSQ14fmg in the
natural system
table4.dat 76 3 Journal of spectroscopic observations
sp/* . 3 The 3 NOT+ALFOSC spectra in FITS format
--------------------------------------------------------------------------------
See also:
J/A+AS/96/269 : Stellar Models from 0.8 to 120 Msolar (Schaller+, 1992)
J/A+AS/98/523 : Grids of stellar models. II. (Schaerer+ 1993)
J/A+AS/101/415 : Grids of stellar models III. (Charbonnel+ 1993)
J/A+AS/141/371 : Low-mass stars evolutionary tracks (Girardi+, 2000)
J/AJ/139/120 : Low-redshift Type-Ia supernovae (Folatelli+, 2010)
J/AJ/139/519 : Carnegie supernova project. SNe Ia (Contreras+, 2010)
J/MNRAS/404/1639 : MILES base models & new line index system (Vazdekis+, 2010)
J/MNRAS/410/585 : SN 2009dc BVRI light curves (Silverman+, 2011)
J/ApJS/200/12 : CfA4: light curves for 94 type Ia SNe (Hicken+, 2012)
J/ApJ/773/53 : Type Ia SNe spectroscopy by the CSP (Folatelli+, 2013)
J/A+A/554/A27 : 2011fe spectrophotometric time series (Pereira+, 2013)
J/A+A/559/A114 : Updated O3N2 and N2 abundance indicators (Marino+, 2013)
J/ApJ/787/29 : UVOT phot. of Super-Chandrasekhar mass SNe Ia (Brown+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/ApJ/795/142 : Defining phot. peculiar SNe Ia (Gonzalez-Gaitan+, 2014)
J/AJ/154/211 : The CSP (DR3): phot. of low-z SNe Ia (Krisciunas+, 2017)
J/A+A/602/A85 : SN 1998bw MUSE datacube (Kruehler+, 2017)
J/ApJ/855/107 : PMAS Integral-field SN hosts COmpilation (Galbany+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.2 d MJD [56925.15/56996.1] Modified Julian Date
10- 15 F6.3 mag Bmag [17.5/21]? B magnitude
17- 21 F5.3 mag e_Bmag [0.008/0.08]? Uncertainty on the Bmag
23- 28 F6.3 mag Vmag [17.3/20.2]? V magnitude
30- 34 F5.3 mag e_Vmag [0.008/0.05]? Uncertainty on the Vmag
36- 41 F6.3 mag rmag [17.25/19.5]? r-band magnitude
43- 47 F5.3 mag e_rmag [0.008/0.025]? Uncertainty on the rmag
49- 54 F6.3 mag imag [17.2/20.1]? i-band magnitude
56- 60 F5.3 mag e_imag [0.01/0.2]? Uncertainty on the imag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 "Y/M/D" Date Observation date (UT)
13- 20 F8.2 d MJD [56924.9/56943.1] Modified Julian Date
22- 31 A10 --- Inst Telescope+Instrument
33- 37 F5.1 d tmaxB [-13.4/3.6] Rest-frame days relative to
B-band maximum
39- 76 A38 --- FileName Name of the FITS file in subdirectory "sp/";
column added by CDS
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Davis et al. CSP-II: NIR type II SNe. 2019ApJ...887....4D 2019ApJ...887....4D
Taddia et al. CSP-II: SN IIn 2013L. 2020A&A...638A..92T 2020A&A...638A..92T
Moriya et al. CSP-II: SN 2014ab. 2020A&A...641A.148M 2020A&A...641A.148M
(End) Emmanuelle Perret [CDS] 03-Jan-2022