Cepheid Variable Stars
Cepheid variable stars were named after the first of their kind observed, δ Cepheus.
Cepheid Variable Stars & Distance Determination
Discovery of the Period - Luminosity Relationship
Calculating Distances Using Cepheids
Standard Candles
The Hubble Key Project ...
Cepheid Variable Stars
Cepheid variable stars are stars that periodically pulsate because of an instability in their internal structure.
Cepheid Variable Stars: A luminous giant star whose brightness varies periodically: growing very bright quickly, and then dimming slowly. The period of variation is related to luminosity.
Cepheid variable stars have masses between five and twenty times the mass of our Sun. The more massive stars are more luminous and have more extended envelopes (the outer layers of gas in a star are sometimes called its "envelope").
Cepheid Variable Stars: A type of luminous giant star whose luminosity varies in a periodic fashion. Cepheids are characterized by a rapid rise in luminosity followed by a slow decline.
RR Lyrae and Cepheid variable stars are recognizable by the characteristic shapes of their light curves.
Some Cepheid variable stars can be found in this constellation: W Sgr is a supergiant which brightness fluctuates every 7 days and 14 hours between 4.4 mag and 5.0 mag.
The supergiant (spectraltype G1.5Ib) U Sgr lies close to center of M25.
period-luminosity relation how the average luminosity of Cepheid variable stars depends on their period of pulsation. photon a distinct ``chunk'' or particle of electromagnetic radiation.
In 1912 the astronomer Henrietta Leavitt (see Fig. 1) observed 20 Cepheid variable stars in the Small Magellanic Cloud (SMC).
In 1929, Edwin Hubble published his conclusion, based on his observations of Cepheid variable stars in distant galaxies, that the universe was expanding.
W VIRGINIS STAR - Another name for Type II Cepheid variable stars.
WADSLEYITE - High pressure polymorph of olivine, β-Mg2SiO4, found on Earth and in some meteorites.
To accomplish this, they used individually resolved Cepheid variable stars within M31. Cepheid variable stars are very useful in calculating distances to many nearby galaxies.
Also included among Population I are the Cepheid variable stars. Cepheids have become one of the standard distance indicators for galactic and extragalactic research through their period-luminosity relation and its validity from galaxy to galaxy.
First the Hubble space telescope found Cepheid variable stars in the Virgo cluster of galaxies, enabling astronomers to get a more accurate distance to that cluster.
Another was the use of Cepheid variable stars to measure the distance to nebulae, which led to the discovery of other galaxies by Edwin Hubble.
Edwin Hubble settled the debate in 1925 when he identified extragalactic Cepheid variable stars for the first time on astronomical photos of M31. These were made using the 2.
Among its primary mission targets was to measure distances to Cepheid variable stars more accurately than ever before, and thus constrain the value of the Hubble constant, the measure of the rate at which the universe is expanding, ...
What does is its changeability, for Zeta Gem is one of the sky's few easily visible "Cepheid variable stars.
Delta Cephei,is a prototype for what are now called Cepheid variable stars. The study of stars such as these helps astronomers determine distance.
On the scale of largest-known stars, Cepheus boasts three in the top five! ...
On 1st January 1925 at a joint meeting of the American Astronomical Society and the American Association for the Advancement of Science, Henry Norris Russell formally made the announcement that Edwin Hubble had discovered Cepheid variable stars in ...
A type of II Cepheid, one of the fainter class of Cepheid variable stars characteristic of Cepheids in globular clusters.
x radiation - (n.)
electromagnetic radiation in the range of approximately 0.05-100 A.
Delta Cephei is the prototype of the Cepheid variable stars, and it is among the closest stars of this type to the Sun (with Polaris being closer).
A graph showing the relation-between period of pulsation and intrinsic brightness among Cepheid variable stars.
Photometer
A device used to measure the intensity and color of light ...
Henrietta Swan Leavitt (1868-1921) was an American astronomer who first described the relationship between the period and the brightness (luminosity) of Cepheid variable stars. She also discovered 1,777 variable stars in the Magellanic Clouds.
Its most celebrated star is Delta Cephei, a pulsating supergiant star that varies in brightness every 5.4 days. It is the prototype of the Cepheid variable stars that astronomers use for estimating distances in space.
For example, the distinct variations of Cepheid variable stars in other galaxies tell us their absolute brightness.
While studying Cepheid variable stars in the SMC, Henrietta Leavitt discovered (1912) the period-luminosity relation. This relation offered a technique for measuring the distances of stars and galaxies. In Feb.
(the largest telescope in the world at the time), proved that the distance from Earth to M31 (also (now) known as the Andromeda Galaxy) was far greater than even the size of Shapley's theoretical universe. Hubble's study of Cepheid variable stars ...
Leavitt discovers Cepheid variable stars.
1920 A.D. Slipher discovers that nebulae are receding.
1923 A.D. Hubble shows that receding nebulae are galaxies.
1938 A.D. Bethe and Weizsäcker suggest stars are powered by nuclear fusion.
1963 A.D.
 See also: Cepheid, Variable star, Cepheid Variable, Cepheid Variable Star, Variable stars
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