What are Variable Stars?

Variable stars are the stars that change in brightness. There are many reasons why variable stars change in brightness but the common ones are eclipsing binary (a companion that comes in front of the star and then moves away) eclipsing binary variable stars are extrinsic, and Pulsating Variables are intrinsic (These stars swell up and then shrink due to internal forces.) Lastly, Cepheid Variable stars are the stars that have a regular cycle of brightness with a frequency related to their luminosity.

for more information on variable stars, please check out the AAVSO site.

Why do we observe Variable Stars?

Variable star astronomy educates us about one of the most significant parts of the universe: the stars. Stars are the fundamental drivers of cosmic evolution, notably in the formation of elements heavier than hydrogen and helium, which comprise us and our Earth. Furthermore, stars and their planet systems are the only likely sites in the cosmos where we will find life; by researching stars (including our own Sun), we are learning about perspective abodes for life. Variable star research is significant because it gives data on stellar parameters like mass, radius, brightness, temperature, internal and exterior structure, composition, and evolution. Some of this data would be difficult or impossible to get in any other manner.

Variable stars that can be observed from North Hemisphere:

Stars that can be seen in summer and autumn only:

Name	RA	Dec	Type	Period	Apparent Magnitude	Constellation
Algol (beta Persei)	3h08m10.14s	+40deg57’20.3″	eclipsing binary	2.87(d)	2.21	Perseus
Beta Lyrae	18h50m04.8s	+33deg21’45.6″	eclipsing binary	13(d)	3.52	Lyra
R Lyrae	18h:55m:20.11s	+43h:56m:45.99s	Pulsating	46(d)	4.00	Lyra

 

Stars that can be seen in Winter and Spring only:

Name	RA	Dec	Type	Period	Apparent Magnitude	Constellation
Epsilon Aurigae	05h01m58.1s	+43d49’23.9″	Eclipsing binary	27 years	3.04	Auriga

 

Stars that can be seen in Fall and Winter only:

Name	RA	Dec	Type	Period	Apparent Magnitude	Constellation
Eta Geminorum	06h14m52.7s	+22deg30’24.5″	semi-regular	233(d)	3.31	Gemini
Zeta Geminorum	07h04m06.5s	+20deg34’13.1″	Cepheid Variable	10.15 (d)	3.93	Gemini

 

Stars that can be seen all year:

Name	RA	Dec	Type	Period	Apparent Magnitude	Constellation
Gamma Cassiopeia	00h56m42.5s	+60d43’00.3″	Spectroscopic binary star	203.5(d)	2.47	Cassiopeia
Delta Cephei	22h29m10.3s	+58d24’14.8″	Cepheid Variable	5.366 (d)	3.75	Cepheus