täht, mille heledus ajas tegelikult või näivalt muutub
star whose brightness (or other physical property such as radius or spectral type) changes over time
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See also: 'Variables: What Are They and Why Observe Them?' American Association of Variable Star Observers. https://www.aavso.org/variables-what-are-they-why-observe-them
Variable stars are classified as either intrinsic, wherein variability is caused by physical changes such as pulsation or eruption in the star or stellar system, or extrinsic, wherein variability is caused by the eclipse of one star by another, the transit of an extrasolar planet (exoplanet), or by the effects of stellar rotation.