SALT spectroscopic classification of PS15cjr (=LSQ15bgf) as a type-IIb supernova near maximum light
ATel #8183; S. W. Jha (Rutgers), Y.-C. Pan, R. J. Foley (Illinois), A. Rest (STScI), D. Scolnic (Chicago/KICP), K. W. Smith, D. Wright, S. J. Smartt (QUB), M. Huber, K. C. Chambers, H. Flewelling, M. Willman, N. Primak, A. Schultz, B. Gibson, E. Magnier, C. Waters, J. Tonry, R. J. Wainscoat (IfA, Hawaii), A. Kniazev (SALT/SAAO)
on 18 Oct 2015; 00:52 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Saurabh Jha (saurabh@physics.rutgers.edu)
Subjects: Optical, Supernovae
We obtained SALT (+RSS) spectroscopy of PS15cjr (=LSQ15bgf) on 2015
Oct 16.9 UT, covering the wavelength range 350-950
nm. Cross-correlation of the spectrum with a template library using
SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows PS15cjr is likely a
type-IIb a few days past maximum light, with a good match to the
spectrum of SN 1993J at +4 days. However, the He I 587.6 nm absorption
is not as strong in PS15cjr as in SN 1993J and SNID also returns
reasonable matches to normal type II-P supernovae like SN 2006bp at an
age of two weeks past maximum.
Adopting a redshift of z = 0.0229 for the host galaxy UGC 2120
(Huchra, Vogeley, & Geller 1999, ApJS, 121, 287) yields an expansion
velocity for PS15cjr of 13,300 km/s, measured to the trough of the
H-alpha P-Cygni profile. This high velocity, combined with
the recently rising light curve, suggests that PS15cjr is young,
and thus we favor the type-IIb classification over a type-II
classification. Further spectroscopic observations are encouraged to
see if the helium features strengthen as expected for a SN IIb.
PS15cjr was independently discovered as part of the Pan-STARRS Survey
for Transients (Huber et al. 2015, ATel #7153). Information on all
PSST objects is available at http://star.pst.qub.ac.uk/ps1threepi/