Question

How are variable stars useful to astronomers? If no variable stars are easily identified in distant galaxies, what do astronomers use to determine distance?

Answer 1

Variable stars are the one ,whose brightness changes periodically.If we observe how much time is required for a variable star to go from bright to dim , back to bright , we can tel how bright the star is .In variable stars , their brightness is connected to their period.

If we know exactly how bright a variable star , and how bright when it looks from earth, one can determine the distance of the star from the earth.Astronomers also use this technique to determine the distance of a variable star in distant galaxy.

Once the period of the variable stars is known, its brightness can be determined.Its apparent magnitude and absolute magnitude are related by distance modules equation.By this equation, Astronomers can determine the Distance of the star from the earth.

If no variable star is identified in the distant galaxy, Astronomers would use stellar parallax technique to determine the distance .

It is a visual effect.when an observer on the earth moves , the nearby objects appear to be shifted relative to distant objects.Now by measuring the angle through which the stars appears to move over the course of the year and knowing how far the earth has moved , the Astronomers are able to determine the star's distance using basic geometry .

Note: If you like my answer , kindly up-vote my answer.This will be a kind of encouragement for me .Thank you.STAY HOME STAY SAFE.