How do astronomers determine the distance to a variable star?
By observing the apparent luminosity, dimmed by the inverse square law of light traveling across the vast reaches of space, and comparing this with the predicted luminosity, astronomers can calculate the distance to that star.
How are Cepheid Variables used in determining distances how far away can they be used quizlet?
Cepheid variables can be used to measure the distances of galaxies as far away as 30 Megaparsecs. Other ways of measuring distance must be used for more distant galaxies. One of the best ways: Type Ia supernovae, which can be used to measure distance up to 3,000 Mpc.
How far away can we use Cepheids to measure distance?
Cepheid variables can be used to measure distances out to about 30 or 40 megaparsecs with the help of the Hubble Space Telescope. There are also two different types of Cepheid variables, and these two types have different period-luminosity relationships.
Why are Cepheid variables used to measure distance?
The important feature of a Cepheid Variable that allows it to be used for distance measurements is that its period is related directly to its luminosity . This relation allows us to work out how much brighter than the Sun the star is.
What are Cepheid variables used for?
Cepheid variable, one of a class of variable stars whose periods (i.e., the time for one cycle) of variation are closely related to their luminosity and that are therefore useful in measuring interstellar and intergalactic distances.
What property of Cepheid variable stars allows one to find the distance to those stars?
This discovery allows one to know the true luminosity of a Cepheid by simply observing its pulsation period. This in turn allows one to determine the distance to the star, by comparing its known luminosity to its observed brightness.
What is a Cepheid variable quizlet?
Cepheid variable are. Stars whose luminosity varies regularly with a period of several days. Unstable stars. Their size is oscilsting (EXPANDING AND CONTRACTING) As the size changes, so does their luminosity and surface temperature.
What kind of stars could be used for determining distance?
While stellar parallax can only be used to measure distances to stars within hundreds of parsecs, Cepheid variable stars and supernovae can be used to measure larger distances such as the distances between galaxies.
What is a Cepheid variable used for?
What do Cepheid variable stars tell us?
Why are Cepheid variable stars good distance indicators?