For refcode 1994A&A...282..731P: Retrieve 91 NED objects in this reference. Please click here for ADS abstract
NED Abstract
Copyright by European Southern Observatory (ESO).
Reproduced by permission
1994A&A...282..731P
Light curves of type II supernovae
II. The analysis
F. Patat, R. Barbon, E. Cappellaro, and M. Turatto
Dipartimento di Astronomia, Universita di Padova, vicolo
dell'Osservatorio 5,135122 Padova, Italy
European Southern Observatory, La Silla, Casilla 19001, Santiago, Chile
Osservntorio Astronomico di Padova, vicolo dell'Osservatorio 5,135122
Padova, Italy
Received 19 July 1993 / Accepted 8 September 1993
Abstract. All photometric observations of Type II Supernovae published to
date, and collected in Paper I, have been reanalyzed along with data from
SN spectroscopy. The light curves are very different both as duration and
slopes of the different portions. For sake of simplicity, the average
decline rates, {beta}_100_, have been used to describe the gross
characteristics of the light curves. It is shown that this simple,
numeric parameter well discriminates among the Plateau and Linear shapes.
Also the color curves are very different, with the Linears
({beta}_100_^B^> 3.5 mag/100^d^) on average bluer than Plateaus
({beta}_100_^B^ < 3.5). The parameter {beta}_100_^BV^, describing the
color evolution, has been computed as {beta}_100_^BV^ = {beta}_100_^B^
{beta}_100_^V^.
By comparing the light curves in absolute magnitude (H_0_ = 75 km s^
1^ Mpc^1^) we confirm that at maximum there is a large dispersion in the
absolute magnitudes, but that the distribution is not uniform: SNII seem
to cluster in at least three groups, with no reference to the light curve
morphology. On the contrary, all but 2 SNII (1987F and 1988Z) converge at
late phases to a similar absolute magnitude. On the hypothesis that the
late light curve is powered by the radioactive decay of ^56^Co, from the
observed dispersion of M_V_ at 300 days we conclude that the amount of
^56^Ni synthesized in the explosion of SNII must be in the range
0.040.10 M_sun_.
With the aim to determine how many parameters are needed to
characterize the properties of SNII, we performed a Multivariate Factor
Analysis on a number of observables, including also some spectroscopic
parameters. It turns out that with only two factors we can explain most
of the variance of the data. In particular, it results that the observed
absolute magnitude is correlated with the relative strength of the
H{alpha} PCygni absorption (measured at 20 days) : bright SNII have
shallow, or negligible, PCygni trough. Also, the maximum absolute
magnitude, M_max_^B^ appears uncorrelated with the color evolution,
{beta}_100_^BV^.
The projection of the SNII in the fundamental plane {beta}_100_^BV^
vs. M_max_^B^ confirms the clustering of SNII in three groups, which we
call Bright (< M_max_^B^ >= 18.7), Regular (16.5) and Faint (14.0)
respectively.
Key words: galaxies: distances and redshifts supernovae: general 
stars: fundamental parameters
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