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RS Puppis, one of the brightest known Cepheid variable stars in the Milky Way galaxy (Hubble Space Telescope) A Cepheid variable (/ ˈ s ɛ f i. ɪ d, ˈ s iː f i-/) is a type of variable star that pulsates radially, varying in both diameter and temperature. It changes in brightness, with a well-defined stable period and amplitude.
In astronomy, a period-luminosity relation is a relationship linking the luminosity of pulsating variable stars with their pulsation period. The best-known relation is the direct proportionality law holding for Classical Cepheid variables, sometimes called the Leavitt Law.
The term s-Cepheid is used for short period small amplitude Cepheids with sinusoidal light curves that are considered to be first overtone pulsators. They are found near the red edge of the instability strip. Some authors use s-Cepheid as a synonym for the small amplitude DCEPS stars, while others prefer to restrict it only to first overtone stars.
Printable version; In other projects ... The following is a list of variable stars that are well-known, ... Classical Cepheid (DCEP) R Aql: Aquila 5 m.5 12 m.0 6.5:
The distance to RS Puppis is important because Cepheids serve as a marker for distances within the Milky Way galaxy and for nearby galaxies.. Because it is located in a large nebula, astronomers using the ESO's New Technology Telescope at La Silla Observatory, Chile have been able to measure its distance in 2008 by strictly geometric analysis of light echoes from particles in the nebula ...
Type II Cepheids are not as well known as their type I counterparts, with only a couple of naked eye examples. In this list, the period quoted for RV Tauri variables is the interval between successive deep minima, hence twice the comparable period for the other sub-types.
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth. The techniques ...
Extragalactic Distance Ladder. Surface brightness fluctuation (SBF) is a secondary distance indicator used to estimate distances to galaxies. It is useful to 100 Mpc ().The method measures the variance in a galaxy's light distribution arising from fluctuations in the numbers of and luminosities of individual stars per resolution element.