Cepheidváltozó

Cepheidváltozó is a type of star that pulsates radially, varying in both diameter and temperature, producing predictable changes in brightness. These stars are crucial tools in astronomy for measuring distances to faraway galaxies. The period of a Cepheid variable's pulsation, meaning the time it takes to complete one cycle of brightening and dimming, is directly related to its intrinsic luminosity. This relationship, known as the period-luminosity relation, was discovered by Henrietta Swan Leavitt in 1908. By measuring the period of a Cepheid, astronomers can determine its absolute magnitude and compare it to its apparent magnitude (how bright it appears from Earth) to calculate its distance. This method, often called the "standard candle" method, was instrumental in Edwin Hubble's discovery that the Andromeda Nebula was actually a separate galaxy far beyond our own Milky Way. There are two main types of Cepheid variables: Type I (classical Cepheids) and Type II (Population II Cepheids), which differ in their metal content and pulsation properties, but both exhibit the period-luminosity relationship.