who proposed such a model?
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do all stars spend the same amount of time on the main sequence The total life span can be estimated, to first approximation, as the total energy produced divided by the star's luminosity. what is main sequence? Continuous and distinctive band of stars that appears on plots of stellar color versus brightness. describe a few of its properties? Majority of stars on a typical HR diagram lie along the main-sequence curve and temperature of a star determines its spectral type mention a few variations in luminosity color? Cepheid variables, Delta Scuti variables, and Beta Cephei variables what is the first variation? A type of star that pulsates radially, varying in both diameter and temperature name a few stars from such variation? UNANSWERABLE what is the anomalous in this variation? A group of pulsating stars on the instability strip have periods of less than 2 days, but with higher luminosities. state the pulsation model in this variation? Pulsation of Cepheids is called the Eddington valve, or "κ-mechanism", where κ (kappa) is the usual symbol for the gas opacity.
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Cepheid variable [SEP] Pulsation model
The accepted explanation for the pulsation of Cepheids is called the Eddington valve, or "κ-mechanism", where the Greek letter κ (kappa) is the usual symbol for the gas opacity. Helium is the gas thought to be most active in the process. Doubly ionized helium (helium whose atoms are missing both electrons) is more opaque than singly ionized helium. The more helium is heated, the more ionized it becomes. At the dimmest part of a Cepheid's cycle, the ionized gas in the outer layers of the star is opaque, and so is heated by the star's radiation, and due to the increased temperature, begins to expand.