The Absolute Magnitude Distributions of Type Ia Supernovae

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Session 57 -- Planetary Nebulae/Supernovae/Ejecta
Display presentation, Thursday, 2, 1994, 9:20-6:30

[57.05] The Absolute Magnitude Distributions of Type Ia Supernovae

Thomas E. Vaughan, David Branch, Douglas L. Miller (Department of Physics and Astronomy, University of Oklahoma), Saul Perlmutter (Lawrence Berkeley Laboratory)

The distributions of blue and visual absolute magnitudes of Type Ia supernovae (SNs Ia) are studied using distances to their parent galaxies as determined by the Tully--Fisher and surface--brightness--fluctuations techniques. The SN Ia sample is found to consist of bright events that have observational absolute magnitude dispersions of $0.3 - 0.4$ mag., plus a smaller number of dim events, some of which were extinguished in the parent galaxy and some of which were intrinsically subluminous. All of the dim supernovae in the sample were spectroscopically peculiar and/or had a red $B-V$ color. SNs Ia that are not known to have been spectroscopically peculiar and are known to have had $B-V$ in the range $-0.25$ to $+0.25$ show observational dispersions $\sigma (M_B) = \sigma (M_V) = 0.30$ mag. This is an upper limit to the intrinsic dispersion among such SNs Ia. The small observational dispersion indicates that SNs Ia, Tully--Fisher, and surface-brightness-fluctuations all give good relative distances to those galaxies which produce SNs Ia.

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