Know About Cepheid Variable

Cepheids are important cosmic benchmarks for scaling galactic and extragalactic distances.

Cepheid variables are a type of star that undergoes periodic changes in brightness. These stars are important in astronomy because they can be used to determine distances to other galaxies, which is crucial in studying the structure and evolution of the universe. Furthermore, Cepheid variables are essential in mapping out the Milky Way as well as other nearby galaxies.

History
Cepheid variables were first discovered by the American astronomer Henrietta Swan Leavitt in 1908. She found that the period of a Cepheid variable's brightness changes was directly related to its intrinsic luminosity. This relationship, known as the period-luminosity relationship, allows astronomers to determine the distance to a Cepheid variable by measuring its period of brightness variation.

Classification Of Cepheid
Cepheid variables are classified as pulsating variable stars, which means that their brightness changes are due to periodic expansions and contractions of their outer layers. This pulsation is caused by the star's internal structure, which is influenced by its mass, age, and composition.
Cepheid variables have been used to measure distances to galaxies beyond our own Milky Way. This was first done by the American astronomer Edwin Hubble in the 1920s, who used Cepheid variables to show that the Andromeda Galaxy was much farther away than previously thought. This discovery helped establish the concept of an expanding universe and paved the way for modern cosmology.
In addition to their importance in measuring distances, Cepheid variables are also interesting objects in their own right. They are relatively rare, with only a few thousand known in our Milky Way galaxy. They are also very luminous, with some Cepheid variables being up to 100,000 times more luminous than our Sun.

Types Of Cepheid
Two Types of Cepheid Variables exist: the Classical Cepheids and the Type II Cepheids. Classical Cepheids are young stars, while Type II Cepheids are older stars. Both types are used to measure distances in the universe.
Type II Cepheids are also used to measure the age of stars in star clusters. Classical Cepheids are more luminous, allowing for more accurate distance measurements. These two types of Cepheid variables are key to understanding the structure of the universe. This helps us to determine the size and age of the universe, as well as to measure the expansion of the universe. By understanding these parameters, we can gain insight into how the universe works.
In conclusion, Cepheid variables are an important type of star that has played a significant role in advancing our understanding of the universe. Their periodic changes in brightness have allowed astronomers to measure distances to other galaxies and to study the properties of these fascinating objects in detail.

By: Sneha Sinha
Class - 9
DAV Public School, Khagaul

Edited by: Thirukumaran Veleyudham