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Date and Time of the Query: 2019-04-25 T06:10:42 PDT
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For refcode 1994A&A...282..731P:
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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 5,1-35122 Padova, Italy European Southern Observatory, La Silla, Casilla 19001, Santiago, Chile Osservntorio Astronomico di Padova, vicolo dell'Osservatorio 5,1-35122 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_^B-V^, describing the color evolution, has been computed as {beta}_100_^B-V^ = {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 0.04-0.10 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} P-Cygni absorption (measured at 20 days) : bright SNII have shallow, or negligible, P-Cygni trough. Also, the maximum absolute magnitude, M_max_^B^ appears un-correlated with the color evolution, {beta}_100_^B-V^. The projection of the SNII in the fundamental plane {beta}_100_^B-V^ 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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