[180.10] HST Cepheid Calibrations of the Luminosity of Ideal SNe Ia and a Redetermination of the Hubble Constant

AAS 207th Meeting, 8-12 January 2006
Session 180 Supernovae and Cosmology
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[180.10] HST Cepheid Calibrations of the Luminosity of Ideal SNe Ia and a Redetermination of the Hubble Constant

A.G. Riess (STScI/JHU), W. Li (UCB), P.B. Stetson (HIA), A.V. Filippenko (UCB), L. Greenhill (SAO), S. Jha (UCB)

We report observations of nearby Type Ia supernovae (SNe~Ia) for which ongoing observations of Cepheid variables in the host galaxies are being obtained with the Hubble Space Telescope. These SNe~Ia triple the sample of ``ideal'' luminosity calibrators: objects with well-observed and well-calibrated light curves of typical shape and with low reddening. By comparing them to all similarly well-measured SNe Ia in the Hubble flow, we have derived a much improved determination of the Hubble constant. A detailed analysis demonstrates that most of the past disagreement over the value of H₀ as determined from SNe~Ia is abated by the replacement of past, problematic data by more accurate and precise, modern data.

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