Variable-Star-Classification
Variable-Star-Classification involves categorizing stars that exhibit changes in brightness over time. These changes can occur due to several reasons such as:
- Pulsation - where the star expands and contracts rhythmically.
- Eclipses - when one star in a binary system blocks the light of another.
- Rotation - where spots or other surface features on a rotating star cause brightness variations.
- Explosions or Eruptions - like in the case of Supernovae or Novae.
History
The study of variable stars began in earnest in the late 19th century. One of the earliest recorded observations was made by the German astronomer Friedrich Wilhelm Argelander in 1838, who noticed that the star Delta Cephei varied in brightness. This led to the discovery of Cepheid Variables, which are crucial for measuring cosmic distances due to their predictable period-luminosity relationship, first noted by Henrietta Leavitt in 1912.
Types of Variable Stars
- Pulsating Variables - These stars expand and contract, causing their brightness to change periodically. Types include:
- Eclipsing Binaries - These are systems where two stars orbit each other, and their light curves show regular dips when one star passes in front of the other. Examples are:
- Rotating Variables - Stars with patches of varying brightness or magnetic fields that affect their light output:
- Explosive or Eruptive Variables - Stars that undergo sudden, often catastrophic changes in brightness:
Importance in Astronomy
Variable stars are invaluable in:
- Determining Stellar Evolution by studying their behavior over time.
- Calculating distances within and beyond our Milky Way galaxy, especially with Cepheid Variables.
- Understanding stellar pulsation mechanisms and the internal structure of stars.
- Providing insights into binary star systems and their interactions.
Resources
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