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Earth and Space Sciences · 术语表

什么是 Cepheid variable; Leavitt law？

又称： Cepheid variable · Leavitt law

Definition 29.16 University Earth and Space Sciences — Year 3 · 第 29 章 — The Milky Way and Galaxies

A Cepheid variable is a young, luminous, pulsating star whose brightness varies with a strictly regular period, from about a day to several weeks. The Leavitt law, or period–luminosity relation, is the linear relation between the mean absolute magnitude of a Cepheid and the logarithm of its period, longer periods for brighter stars.

The Leavitt law in the Large Magellanic Cloud: the Wesenheit index of 2315 Cepheids pulsating in their fundamental mode against the logarithm of their period (OGLE survey, Soszyński and others, 2015, via the CDS). Brighter stars are higher. A straight line fitted by least squares, after setting aside 92 stars more than three standard deviations from it, reproduces the published relation (-3.314, 15.888). With the Cloud’s distance modulus, 18.477, the line gives the absolute Wesenheit magnitude of any Cepheid from its period. — The Leavitt law in the Large Magellanic Cloud: the Wesenheit index of 2315 Cepheids pulsating in their fundamental mode against the logarithm of their period (OGLE survey, Soszyński and others, 2015, via the CDS). Brighter stars are higher. A straight line fitted by least squares, after setting aside 92 stars more than three standard deviations from it, reproduces the published relation ( $-3.314$ , $15.888$ ). With the Cloud’s distance modulus, 18.477, the line gives the absolute Wesenheit magnitude of any Cepheid from its period.

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