What property of Cepheid and RR Lyrae type variable stars makes them useful for measuring distances?

period-luminosity relation Light curves of these stars show that their luminosities vary with a regularly repeating period. RR Lyrae stars can be used as standard bulbs, and cepheid variables obey a period-luminosity relation, so measuring their periods can tell us their luminosities.

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Then, who won the great debate?

After the debate Later in the 1920s, Edwin Hubble showed that Andromeda was far outside the Milky Way by measuring Cepheid variable stars, proving that Curtis was correct. Subsequently, what did a major discovery made by harlow shapley using rr lyrae stars and globular clusters establish? What did a major discovery made by Harlow Shapley using RR Lyrae stars and globular clusters establish? Cepheid variables can be used to determine the distances to the nearest galaxies. The stars in the halo move in randomly-oriented orbits, while the disk stars generally stay confined to moving in the disk.

What do the red stars in the galactic halo tells us about galaxy formation?

What do the red stars in the Galactic halo tell us about the history of the Milky Way? This tells us the original shape of the cloud of gas that was the galaxy before stars formed. The entire halo appears to rotate, which further tells us that this cloud was rotating. Consequently, how do stars in the disk of the milky way move quizlet? -Stars in the disk all orbit in the same direction with a little up-and-down motion.

Then, what does the luminosity of a main sequence star tell us quizlet?

Luminosity classes of stars are designated by Roman numerals and tell us what region of the H-R diagram the star falls in. We use both spectral type and luminosity class to completely classify stars; the spectral type tells us the star's temperature while the luminosity class tells us its radius. What is the major difference between an elliptical galaxy and a spiral galaxy quizlet? The major difference between spiral and elliptical galaxies is that elliptical galaxies lack a significant disk component, although both types have the halo component.

Stars are born in the interstellar medium by the gravitational collapse of gas and dust within interstellar molecular clouds which have mass many times greater than the mass of a single star.