NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-25 T13:26:59 PDT
Help | Comment | NED Home

For refcode 1996ApJ...460L..15S:
Retrieve 13 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
1996ApJ...460L..15S CEPHEID CALIBRATION OF THE PEAK BRIGHTNESS OF TYPE Ia SUPERNOVAE: CALIBRATION OF SN 1990N IN NGC 4639 AVERAGED WITH SIX EARLIER TYPE Ia SUPERNOVA CALIBRATIONS TO GIVE H_0_ DIRECTLY ALLAN SANDAGE, A. SAHA, G. A. TAMMANN, LUKAS LABHARDT, N. PANAGIA, AND F. D. MACCHETTO Received 1995 November 22; accepted 1996 January 11 ABSTRACT Periods and light curves have been measured with the Hubble Space Telescope for 20 Cepheids in NGC 4639, parent galaxy to the Type Ia, prototypical supernova SN 1990N. The periods range from 17 to 69 days. The mean apparent magnitudes, averaged over the light curves, range from <V> = 25.6 to <V> = 27.3. Well-determined period-luminosity relations exist in V and I. Corrected for differential extinction, these give a true modulus for NGC 4639 of (m - M)_0_ = 32.00 +/- 0.23. Combining the light curves for SN 1990N with this modulus gives M_B_(max) = -19.30 +/- 0.23 and M_V_(max) = -19.39 +/- 0.23. This, together with six previous calibrations of Type Ia supernovae, gives the mean calibrations of "Branch normal" supernovae to date as <M_B_(max)> = - 19.47 +/- 0.07 and <M_V_(max)> = - 19.48 +/- 0.07. The resulting Hubble constants, reading the Type Ia supernova Hubble diagrams at very large redshifts beyond any possible local velocity anomalies, give global values of the Hubble constant of H_0_(B) = 56 +/- 4 (internal) km s^-1^ Mpc^-1^ and H_0_(V) = 58 +/- 4 (internal) km s^-1^ Mpc^-1^. Subject headings: Cepheids - distance scale - galaxies: individual (NGC 4639)
Retrieve 13 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home