A. Pastorello, M. L. Pumo, H. Navasardyan, L. Zampieri, M. Turatto, J. Sollerman, F. Taddia, E. Kankare, S. Mattila, J. Nicolas, E. Prosperi, A. San Segundo Delgado, S. Taubenberger, T. Boles, M. Bachini, S. Benetti, F. Bufano, E. Cappellaro, A. D. Cason, G. Cetrulo, M. Ergon, L. Germany, A. Harutyunyan, S. Howerton, G. M. Hurst, F. Patat, M. Stritzinger, L. -G. Strolger, W. Wells
In this paper we investigate the properties of SN 2009E, which exploded in a
relatively nearby spiral galaxy (NGC 4141) and that is probably the faintest
1987A-like supernova discovered so far. Spectroscopic observations which
started about 2 months after the supernova explosion, highlight significant
differences between SN 2009E and the prototypical SN 1987A. Modelling the data
of SN 2009E allows us to constrain the explosion parameters and the properties
of the progenitor star, and compare the inferred estimates with those available
for the similar SNe 1987A and 1998A. The light curve of SN 2009E is less
luminous than that of SN 1987A and the other members of this class, and the
maximum light curve peak is reached at a slightly later epoch than in SN 1987A.
Late-time photometric observations suggest that SN 2009E ejected about 0.04
solar masses of 56Ni, which is the smallest 56Ni mass in our sample of
1987A-like events. Modelling the observations with a radiation hydrodynamics
code, we infer for SN 2009E a kinetic plus thermal energy of about 0.6 foe, an
initial radius of ~7 x 10^12 cm and an ejected mass of ~19 solar masses. The
photospheric spectra show a number of narrow (v~1800 km/s) metal lines, with
unusually strong Ba II lines. The nebular spectrum displays narrow emission
lines of H, Na I, [Ca II] and [O I], with the [O I] feature being relatively
strong compared to the [Ca II] doublet. The overall spectroscopic evolution is
reminiscent of that of the faint 56Ni-poor type II-plateau supernovae. This
suggests that SN 2009E belongs to the low-luminosity, low 56Ni mass, low-energy
tail in the distribution of the 1987A-like objects in the same manner as SN
1997D and similar events represent the faint tail in the distribution of
physical properties for normal type II-plateau supernovae.
View original:
http://arxiv.org/abs/1111.2497
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