J/A+A/588/A1 Supernova LSQ13fn (Polshaw+, 2016)
LSQ13fn: A type II-Plateau supernova with a possibly low metallicity progenitor
that breaks the standardised candle relation.
Polshaw J., Kotak R., Dessart L., Fraser M., Gal-Yam A., Inserra C.,
Sim S.A., Smartt S.J., Sollerman J., Baltay C., Rabinowitz D., Benetti S.,
Botticella M.T., Campbell H., Chen T.-W., Galbany L., McKinnon R.,
Nicholl M., Smith K.W., Sullivan M., Takats K., Valenti S., Young D.R.
<Astron. Astrophys. 588, A1 (2016)>
=2016A&A...588A...1P 2016A&A...588A...1P (SIMBAD/NED BibCode)
ADC_Keywords: Supernovae ; Spectroscopy
Keywords: supernovae: general - supernovae: individual: LSQ13fn
Abstract:
We present optical imaging and spectroscopy of supernova (SN) LSQ13fn,
a type II supernova with several hitherto-unseen properties. Although
it initially showed strong symmetric spectral emission features
attributable to HeII, NIII, and CIII, reminiscent of some interacting
SNe, it transitioned into an object that would fall more naturally
under a type II-Plateau (IIP) classification. However, its spectral
evolution revealed several unusual properties: metal lines appeared
later than expected, were weak, and some species were conspicuous by
their absence. Furthermore, the line velocities were found to be lower
than expected given the plateau brightness, breaking the SN IIP
standardised candle method for distance estimates. We found that, in
combination with a short phase of early-time ejecta-circumstellar
material interaction, metal-poor ejecta, and a large progenitor radius
could reasonably account for the observed behaviour. Comparisons with
synthetic model spectra of SNe IIP of a given progenitor mass would
imply a progenitor star metallicity as low as 0.1Z☉. LSQ13fn
highlights the diversity of SNe II and the many competing physical
effects that come into play towards the final stages of massive star
evolution immediately preceding core-collapse.
Description:
Reduced spectra of LSQ13fn. The spectra are in ascii format, and have
not been corrected for reddening or host galaxy recession. The
filenames refer to the date of the observations.
Objects:
-----------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------
11 51 17.29 -29 36 41.1 LSQ13fn = LSQ 13fn
-----------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea5.dat 98 12 Log of the spectroscopic observations of LSQ13fn
sp/* . 12 Individual spectra
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "date" Obs.Date Observation date
12- 18 F7.1 d MJD Modified Julian date
20- 24 F5.1 d Epoch Epoch relative to the date of maximum
brightness (MJD=56306.21) in the rest frame
of the SN
26- 45 A20 --- Tel Telescope + instrument
47- 50 I4 0.1nm b_lambda Wavelength range
51 A1 --- --- [-]
52- 56 I5 0.1nm B_lambda Wavelength range
58- 70 A13 --- ExpTime Exposure time(s) in second unit
72- 74 F3.1 arcsec Slit Slit width
76- 79 F4.1 0.1nm Res Resolution (1)
80 A1 --- --- [,]
82- 85 F4.1 0.1nm Res2 ? Second resolution (1)
87- 98 A12 --- FileName Name of the spectrum file in subdirectory sp
--------------------------------------------------------------------------------
Note (1): Resolution, as measured from the FWHM of the sky lines. Note that the
NTT spectra at 5.7d and 15.1d are not presented in Fig. 4 as they were taken
in poor conditions and the supernova signal is weak.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: sp/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 F12.6 0.1nm lambda Wavelength
14- 26 E13.7 10mW/m2/nm Flux Flux (in erg/cm2/s/Å)
--------------------------------------------------------------------------------
Acknowledgements:
Joseph Polshaw, jpolshaw01(at)qub.ac.uk
(End) Joseph Polshaw [QUB, UK], Patricia Vannier [CDS] 19-Feb-2016