[vsnet-chat 940] Re:Expected SN Ia Maximum Magnitude in M96

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

Taichi Kato wrote:

>>"Expected SN Ia maximum in M96

 T & B Supernova Search Chart gives the expected maximum of SN Ia in M96
of 11.7, while Yamaoka gives 10.7 (aside from the Cosmolgical Supernova
Maximum Calculator ...).  What is the difference in their assumptions?"<<

Kato-san:

You bring up a good observation! While my estimates are in near agreement
with Mr. Hitoshi's, (of course sans any line-of-sight absorption, or where
in the host galaxy the event took place, etc., which is irrelevant for
_theorized_ estimating at this point)  I have a humble opinion that I would
like to share. I must retreat to a disclaimer that this discussion might
not be the most difinitive answer to your question, but rather an attempt
to find out the reason, why?

The Thompson/Bryan charts use a distance moduli that is consistant with a
~95km/sec/Mpc scenario, and their estimated V magnitude absolute luminosity
(there are some differances compared to B [blue-light maximum] but in most
cases they are very small {ie.exceptions: SN 1990Y and 1992K where the
differance was 0.33m and 0.74m respectively} for SNe was calculated,
thusly: -18.5 for a type Ia, and -16.5 for a type II event (Appendix III of
the T/B Handbook).

My source for most SNe data utilizes data from other "camp"
(Ho=50km/sec/Mpc) mainly because I have more reference material involving
same <g>. In this case a theorized SNe absolute maximum (general) value of
-20 for a type Ia and -18.0 for a type II event is used (Of course this has
changed after having correspondance with you and Mr. Hitoshi and doing some
research on my own [see Hamuy et. al AJ_112(6),2438-2447, Dec., 1996 and
Hamuy et. al AJ _112_(6),2391-2397, Dec., 1996]. Most recently, I now favor
a theorized absolute value of -19.8 for type Ia's and a -18.8 for type II's
(from a moderate sub-sample). This of course is administered to the
respective distance moduli of that "camp". So to make a long story
short....I think that perhaps some of the data might have been mixed in the
T/B data involving M96? 

We must consider one thing when comparing the two "camps".... any values
used in conjunction with estimating a theorized SNe magnitude must remain
within that camp. I have seen some folks mix and match, and their
data/information then becomes questioned....just a thought!

Best Regards,

Steve

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