High Quality Content by WIKIPEDIA articles! X Sagittarii is a Cepheid variable star in the constellation Sagittarius. This variable star changes in apparent magnitude from +4.24 to +4.84 with a period of 7.01 days. Its change in brightness is accompanied by a change in spectral classification, from G2 to F5. A Cepheid is a member of a class of pulsating variable stars. The relationship between a Cepheid variable's luminosity and pulsation period is quite precise, securing Cepheids as viable standard candles and the foundation of the Extragalactic Distance Scale. Typical classical Cepheids pulsate with periods of a few days to months, and their radii change by several million kilometers (30%) in the process. They are large, luminous stars, of spectral class F6 – K2, they are 5–20 times as massive as the Sun and up to 30000 times more luminous.

Данное издание не является оригинальным. Книга печатается по технологии принт-он-деманд после получения заказа.