High Quality Content by WIKIPEDIA articles! X Andromedae is a variable star in the constellation of Andromeda. It is classified as a Mira variable, and varies from an apparent visual magnitude of 15.2 at minimum brightness to a magnitude of 8.5 at maximum brightness, with a period of approximately 343.4 days. A star is classified as variable if its apparent brightness as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth. Many, possibly most, stars have at least some variation in luminosity: the energy output of our Sun, for example, varies by about 0.1% over an 11 year solar cycle, equivalent to a change of one thousandth of a magnitude.

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