SN 2009kn - the twin of the Type IIn supernova 1994W
Journal article, 2012
We present an optical and near-infrared photometric and spectroscopic study of supernova (SN) 2009kn spanning ˜1.5 yr from the discovery. The optical spectra are dominated by the narrow (full width at half-maximum ˜1000 km s-1) Balmer lines distinctive of a Type IIn SN with P Cygni profiles. Contrarily, the photometric evolution resembles more that of a Type IIP SN with a large drop in luminosity at the end of the plateau phase. These characteristics are similar to those of SN 1994W, whose nature has been explained with two different models with different approaches. The well-sampled data set on SN 2009kn offers the possibility to test these models, in the case of both SN 2009kn and SN 1994W. We associate the narrow P Cygni lines with a swept-up shell composed of circumstellar matter and SN ejecta. The broad emission line wings, seen during the plateau phase, arise from internal electron scattering in this shell. The slope of the light curve after the post-plateau drop is fairly consistent with that expected from the radioactive decay of 56Co, suggesting an SN origin for SN 2009kn. Assuming radioactivity to be the main source powering the light curve of SN 2009kn in the tail phase, we infer an upper limit for 56Ni mass of 0.023 Msun. This is significantly higher than that estimated for SN 1994W, which also showed a much steeper decline of the light curve after the post-plateau drop. We also observe late-time near-infrared emission which most likely arises from newly formed dust produced by SN 2009kn. As with SN 1994W, no broad lines are observed in the spectra of SN 2009kn, not even in the late-time tail phase.
supernovae: general
supernovae: individual: SN 2009kn
supernovae: individual: SN 1994W
Author
E. Kankare
Tuorla Observatory
Nordic Optical Telescope
M Ergon
Stockholm University
F Bufano
Istituto nazionale di astrofisica (INAF)
J Spyromilio
European Southern Observatory (ESO)
S. Mattila
Tuorla Observatory
N. N. Chugai
Russian Academy of Sciences
P. Lundqvist
Stockholm University
A. Pastorello
Queen's University Belfast
Istituto nazionale di astrofisica (INAF)
R Kotak
Queen's University Belfast
S. Benetti
Istituto nazionale di astrofisica (INAF)
M.-T. Botticella
Queen's University Belfast
Istituto nazionale di astrofisica (INAF)
Robert Cumming
Chalmers, Earth and Space Sciences, Onsala Space Observatory
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
C. Fransson
Stockholm University
M Fraser
Queen's University Belfast
G. Leloudas
Dark Cosmology Centre
Stockholm University
M Miluzio
Istituto nazionale di astrofisica (INAF)
J Sollerman
Stockholm University
M. Stritzinger
Aarhus University
M. Turatto
Osservatorio Astronomico di Trieste
S Valenti
Queen's University Belfast
Istituto nazionale di astrofisica (INAF)
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 424 2 855-873Subject Categories
Astronomy, Astrophysics and Cosmology
Roots
Basic sciences
Infrastructure
Onsala Space Observatory
DOI
10.1111/j.1365-2966.2012.21224.x