Blazhko

Blazhko is a term referring to a type of modulation observed in pulsating stars. Pulsating stars, also known as variable stars, are stars that change in brightness over time. One of the most well-known types of pulsating stars is the RR Lyrae star.

In the 1900s, the Russian astronomer Sergey Blazhko discovered a peculiar behavior in some RR Lyrae stars. These stars, which are used as standard candles in astronomy to measure distances to other galaxies, exhibited periodic variations in brightness. However, the amplitude of these brightness variations was not constant, but instead showed a periodic change.

This change in amplitude of the brightness variations is what is now known as Blazhko modulation. The Blazhko effect is characterized by periodic changes in the star's brightness variations, typically on a timescale of months or years. These changes can be detected using photometry, which is the measurement of the amount of light a star emits.

The Blazhko effect is still not fully understood, and it is the subject of ongoing research in the field of stellar astronomy. Some theories suggest that the Blazhko effect may be caused by changes in the star's internal structure or atmosphere, while others propose that it may be related to the star's environment, such as its proximity to other stars or its motion through the galaxy.

Studying the Blazhko effect can provide valuable insights into the internal workings of pulsating stars and the behavior of RR Lyrae stars in particular. These stars are important tools for astronomers, as they can be used to measure distances to other galaxies and study the evolution of the universe.