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Classical Cepheids (also known as Population I Cepheids, type I Cepheids, or Delta Cepheid variables) undergo pulsations with very regular periods on the order of days to months. Classical Cepheids are Population I variable stars which are 4–20 times more massive than the Sun, [ 24 ] and up to 100,000 times more luminous. [ 25 ]
Classical Cepheids are also known as Population I Cepheids, Type I Cepheids, and Delta Cepheid variables. There exists a well-defined relationship between a classical Cepheid variable's luminosity and pulsation period, [ 1 ] [ 2 ] securing Cepheids as viable standard candles for establishing the galactic and extragalactic distance scales .
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.
Type II Cepheids are variable stars which pulsate with periods typically between 1 and 50 days. [ 1 ] [ 2 ] They are population II stars: old, typically metal-poor, low mass objects. [ 1 ]
W Virginis is the prototype W Virginis variable, a subclass of the Cepheid variable stars. It is located in the constellation Virgo, and varies between magnitudes 9.46 and 10.75 over a period of approximately 17 days.
W Virginis variables are a subclass of Type II Cepheids which exhibit pulsation periods between 10–20 days, [1] and are of spectral class F6 – K2. [ 2 ] [ 3 ] They were first recognized as being distinct from classical Cepheids by Walter Baade in 1942, in a study of Cepheids in the Andromeda Galaxy that proposed that stars in that galaxy ...
The maximum semaglutide dose for weight loss is 2.4 milligrams (mg) per week. Your healthcare provider will start you on a lower weekly dose and gradually increase it over time.
The unqualified term instability strip usually refers to a region of the Hertzsprung–Russell diagram largely occupied by several related classes of pulsating variable stars: [1] Delta Scuti variables, SX Phoenicis variables, and rapidly oscillating Ap stars (roAps) near the main sequence; RR Lyrae variables where it intersects the horizontal branch; and the Cepheid variables where it crosses ...