[vsnet-chat 790] (vsnet-chat 788) Re: Supernovae

["Steve H. Lucas" <76620.1721@compuserve.com>]

Berto Monard wrote:

>>"Does anyone of you know if there exist any research findings re: the
frequency of SN occurrence in elliptical galaxies as compared to spirals or
other types."<<

Yes! as a matter of fact just last year an interesting and informative
paper was published by E. Cappellaro (Univ. of Padova) et. al entitled:
"The Rate of Supernovae From The Combined Sample of Five Searches"
(A&A_322_,431-441(1997).

This paper outlined the results of the Asiago, Crimea, Bob Evans, OCA
(Observatoire de la Cote d' Azur), and the Calan/Tololo search initiatives.

Some conclusions of the 110 SNe discovered in a sample of 7773 RC3 galaxies
indicate: (direct quote from the above source)

A.) The rate of SNIa ellipticals,0.13 SNu is confirmed to be lower than
that in spirals.
B.) The most prolific galaxies are late spirals where 2/3 of the SNe are of
type II (0.88 SNu)
C.) SN Ib/c are relatively rare, being at most 40% of all SN I (0.16 SNu in
late spirals).
D.) If SNe 1991bg and 1987A are considered the prototypes of separate
classes of faint SNIa and SNII respectively, the overall SN rates should be
raised by only 20-30%.
E.)The average frequency of SN IIn in spirals is <0.03 SNu. The fact that
they constitute about 20% of all SNII presently discovered is due to their
high intrinsic brightness.

(Note: SNu is indicated as: [SNe per 10^10 L (o) per century]) inferring
Ho=75km/sec per Mpc.
{(o)=solar mass}

A thumbnail sketch of the statistics (also from the article) are:

Galaxy          SN Rate(SNu)

E               0.13
SO              0.18
SOa-Sa          0.57
Sab-Sb          0.78
Sbc-Sc          1.19
Scd-Sd          1.49
Others          0.90

Of course the breakdown is more extensive and detailed in the article as to
types for each galaxy type, but it would seem to indicate from the above
data that the numbers of events seem to increase respectively with evolved
galaxy types???

Best Regards,

Steve H. Lucas
International Supernovae Network

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