Classical Cepheid variable
Classical Cepheid variables, also known as Type I variables, or Delta Cephei variables undergo pulsations with very regular periods on the order of days to months, and are a standard candle. These Cephids are population I, yellow supergiants, and are up to 30,000 times more luminous than the sun. Their luminosity is directly related to their period of variation, with a slight dependence on metallicity as well. The longer the pulsation period, the more luminous the star. Once this period-luminosity relationship is calibrated, the luminosity of a given Cepheid whose period is known can be established. Their distance is then easily found from their apparent brightness. Observations of Classical Cepheid variables are used for determining distances to galaxies within the Local Group and beyond. [1][2][3]
Classical Cepheids are supergiants of spectral class F6 – K2 and their radii change by (~25% for the longer-period l Car) millions of kilometers during a pulsation cycle.[4][5]
References
- ^ Turner, David G."The Progenitors of Classical Cepheid Variables". JRASC (1996)
- ^ Turner, David G."The PL calibration for Milky Way Cepheids and its implications for the distance scale". Ap&SS (2010)
- ^
"delta Cephei and Cepheid Variables". Physics, and astrophyics. Georgia State University. November 2010. Retrieved 2010-11.
{{cite web}}: Check date values in:|accessdate=(help) - ^ Rodgers, A. W.; "Radius variation and population type of cepheid variables". Monthly Notices of the Royal Astronomical Society. 117 (1956) 84–94
- ^ W. Strohmeier, Variable Stars, Pergamon (1972)
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