[vsnet-chat 945] Re: Expected SN Ia Magnitude in M96

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

Supernovae Chatters:

I must mention that there were some mysterious additions to my earlier post
ie.>>"(Ho=3D50km/sec/Mpc)<<" Somehow "3D" was added, plus my message to the
ISN Chat was bounced back to me....is my CPU acting up? Solar activity at
time of transmission, gremlins? <g> in any event.....

Mr. Hitoshi wrote:

>>"On the other hand, the distance estimate using recession velocity is
very dangerous and will give a mis-leading results when we adopt it to
nearby galaxies"<<

This is very true, but in a general sense for roughly estimating SN maximum
magnitudes I think we can honestly say that such values will at least give
"ballpark" estimates (ie. pretty close, but not critical).

Mr. Hitoshi also wrote:

>>" Instead, we should use the distance estimated by other method (T-F
relation, Cepheid, and so on) and compare it with the Virgo distance
derived by HST (16 - 17 Mpc).  For M96 case, the catalogued distance was
8.1 Mpc (Turry, Nearby Galaxy Catalog), which implies that a object in M96
will be seen brighter about 1.6 mag than
it were in Virgo It gives my predicted maximum of SN 1998bu (12.3 -1.7 =
10.6). "<<

 Along those same lines (as above), here lies the differances in the
various sources of information at our disposal. Tully-Fisher (amongst
others) have championed an Ho near 100km/sec/Mpc (if my memory serves me
correctly). My source of information in this instance is the
_Shapley-Ames_Catalog of Galaxies (Ho=50km/sec/Mpc). If we take the general
distance modulus of the Virgo Cluster as being DM=31.7 (determined from
Cluster A [M87], and Cluster B [M49] which would _roughly_ yield to us the
centroid of said Cluster) I get a distance of 21.87Mpc. A type Ia SN would
roughly (theoretically) peak at ~11.9. For M96, DM=30.9, which according to
my calculations would give us a distance of ~15.13Mpc., I therefore
estimate a rough SN Ia maximum of 11.1 (utilizing my revised absolute value
of -19.8). 

>>" the light curves of SN will show different shapes in different color
bands."<<

This is so very true! Take for instance the classical linear type II event
SN 1979C, which showed absolutely NO plateau phase in V or B, yet was
observed in the "R" band to have one!! This could cause some trouble.....

To Mr. Hitoshi:

In the case of type Ia's It seems to me that most of the "fireworks" on the
light curves start after about day No. 4 involving colors and data yielded
from various bands of observation that are used. Since I am an observer who
must utilize what I can see ie. the V band, I have come up with some
conclusions that I was enlightened with when I had correspondance with you
and Mr. Kato. I did some homework and it my humble opinion after reading
the data from Hamuy et. al's paper _The Morphology of Type Ia SNe Light
Curves_, (AJ.,_112(6), December, 1996, 2438-2447) I must conclude that
using SN Ia as a primary distance indicators should come under more
scrutiny.....

Very Best Regards,

Steve

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