From: Robert A. Knop Jr. (robert.a.knop@vanderbilt.edu)
Date: Sun Mar 28 2004 - 17:10:20 PST
On Sun, Mar 28, 2004 at 04:37:54PM -0800, Lifan Wang wrote:
> I do not believe R-I can be anywhere close to -0.4 at optical
> maximum of a normal SN Ia. My light curve fits show most of the SNe
> with z
> < 0.005 show -0.24 at B-max. R-I = -0.4 is beyond reasonable physics.
Here's your problem.
Whatever you believe your understanding of the physics of supernovae
is, the simple fact is that many supernovae are observed to have
R-I~-0.4 around maximum. Both Serena and I have seen it. Observations
are going to trump preconceptions about what the physics ought to be
every time.
Here are some of the colors I have (note that some of these suffer a
little host galaxy extinction, too!)
SN stretch epoch color (R-I)
--------------------------------------
1994M 0.887 3.3 -0.43 +- 0.04
1994S 1.035 0.9 -0.49 +- 0.06
1994ae 1.010 -0.4 -0.42 +- 0.04
1994ae 1.010 0.6 -0.45 +- 0.04
1995D 1.118 -1.0 -0.30 +- 0.05
1995D 1.118 -0.2 -0.27 +- 0.07
1995D 1.118 1.7 -0.38 +- 0.06
1995al 1.084 0.5 -0.35 +- 0.06
1995al 1.084 1.4 -0.35 +- 0.08
1995ac 1.090 -2.5 -0.21 +- 0.04
1995ac 1.090 0.0 -0.29 +- 0.05
1995bd 1.040 0.3 -0.35 +- 0.04
1995bd 1.040 1.2 -0.42 +- 0.05
1996X 0.901 0.2 -0.32 +- 0.03
1996X 0.901 1.3 -0.37 +- 0.04
1996bl 1.033 -1.6 -0.23 +- 0.04
1996bo 0.841 -1.6 -0.34 +- 0.01
1996bo 0.841 0.7 -0.31 +- 0.01
1992al 0.958 1.7 -0.40 +- 0.04
1992bc 1.081 1.4 -0.50 +- 0.03
1992bo 0.737 0.0 -0.27 +- 0.04
1992bo 0.737 1.3 -0.32 +- 0.05
-Rob
-- --Prof. Robert Knop Department of Physics & Astronomy, Vanderbilt University robert.a.knop@vanderbilt.edu
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