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Astron. Astrophys. 325, 871-876 (1997)

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Using distant type Ia supernovae to measure the cosmological expansion parameters *

Robert Tripp

Institute for Nuclear and Particle Astrophysics, Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

Received 14 August 1996 / Accepted 6 September 1996


A comprehensive analysis of two recent collections of distant Type Ia supernovae is presented. The method used is both simple and rigorous. Correcting the absolute magnitudes for the measured decline rates yields in nearly all cases a dispersion consistent with measurement uncertainties, showing from these data that Type Ia supernovae are remarkably reliable standardized candles. With 26 supernovae between [FORMULA] and a cosmological sample of six supernovae between [FORMULA], the Cepheid-based Type Ia supernova absolute magnitude scale leads to a Hubble constant [FORMULA] km s-1 Mpc-1 and a deceleration constant q0 of 0.385 [FORMULA] 0.36. We note the implications of these results for the age of the universe both with and without the introduction of a cosmological constant. This leads to further constraints on the mass density [FORMULA] of the universe when comparison is made with the age of the universe derived from globular clusters.

Key words: supernovae: general – cosmology: observations – distance scale

* This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Division of High Energy Physics of the U.S. Department of Energy under Contract DE-AC03-76SF00098

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© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998