منابع مشابه
The Hubble Constant
Considerable progress has been made in determining the Hubble constant over the past two decades. We discuss the cosmological context and importance of an accurate measurement of the Hubble constant, and focus on six high-precision distance-determination methods: Cepheids, tip of the red giant branch, maser galaxies, surface-brightnes fluctuations, the TullyFisher relation and Type Ia supernova...
متن کاملThe Hubble Constant
I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of t...
متن کاملDetermination of the Hubble constant.
Establishing accurate extragalactic distances has provided an immense challenge to astronomers since the 1920s. The situation has improved dramatically as better detectors have become available, and as several new, promising techniques have been developed. For the first time in the history of this difficult field, relative distances to galaxies are being compared on a case-by-case basis, and th...
متن کاملThe Hubble Constant from the Gravitational Lens
We present a refined gravitational lens model of the four-image lens system B1608+656 based on new and improved observational constraints: (i) the three independent time-delays and flux-ratios from Very Large Array (VLA) observations, (ii) the radio-image positions from Very Large Baseline Array (VLBA) observations, (iii) the shape of the deconvolved Einstein Ring from optical and infrared Hubb...
متن کاملCepheid metallicity and Hubble constant
This study combines data from a set of seven Cepheid-calibrated galaxies in Virgo, Leo I and Fornax and four supernovæ with known metallicities, including metallicity corrections to the Cepheid distances, in order to determine a consistent mean value for the Hubble constant. We derive Virgo and Coma distances over different paths, starting from the metallicity corrected Cepheid distances of Vir...
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ژورنال
عنوان ژورنال: Publications of the Astronomical Society of Australia
سال: 2000
ISSN: 1323-3580,1448-6083
DOI: 10.1071/as00045a