TheHubble Space TelescopeKey Project on the Extragalactic Distance Scale. XIV. The Cepheids in NGC 1365

The Extragalactic Distance Scale without Cepheids

Distances of galaxies in the Hubble Space Telescope Key Project are based on the Cepheid period-luminosity relation. An alternative basis is the tip of the red giant branch. Using archival HST data, we calibrate the infrared TullyFisher relation using 14 galaxies with tip of the red giant branch measurements. Compared with the Key Project, a higher value of the Hubble Constant by 10% ± 7% is in...

The Extragalactic Distance Scale

Significant progress has been made during the last 10 years toward resolving the debate over the expansion rate of the Universe. The current value of the Hubble parameter, H 0, is now arguably known with an accuracy of 10%, largely due to the tremendous increase in the number of galaxies in which Cepheid variable stars have been discovered. Increasingly accurate secondary distance indicators, m...

The Extragalactic Distance Scale

Cepheid variables are used to derive a Virgo cluster distance of 16.0 ± 1.5 Mpc. In conjunction with the Coma velocity and the well-established Coma/Virgo distance ratio, this yields a Hubble parameter H = 81 ± 8 km s o-1 Mpc. By combining this value with an age of the Universe / 16.8 ± 2.1 Gyr, that-1 is derived from the metal-poor globular cluster M92, one obtains f (5, %) / 1.39 ± 0.22. This...

Calibration of the Distance Scale from Cepheids

The Discovery of Cepheids and a Distance to Ngc

We discuss a new distance to NGC 5128 (Centaurus A) based on Cepheid variables observed with the Hubble Space Telescope. Twelve F555W (V ) and six F814W (I) epochs of cosmic-ray-split Wide Field Planetary Camera 2 observations were obtained. A total of 56 bona-fide Cepheids were discovered, with periods ranging from 5 to ∼ 50 days; five of these are likely Population II Cepheids of the W Virgin...