How do we measure distances between galaxies?

Question

How do we measure distances between galaxies?
In this context explain the roles of variable stars, supernovae, the Tully-Fisher relation and the Hubble flow.

Answer 1

Hi. One step at a time. We use parallax to find the distance to Cepheid variables, the brightness of Cepheid variables to find the distance to near galaxies, the brightness of those galaxies to find more distant galaxies distance, and certain types of very bright supernovae to find even greater distances. The average brightnesses learned from these studies allows for even more distant galaxies distance to be determined. The Hubble expansion constant allows for determination from red shift of the spectral lines.

Answer 2

Astronomers estimate distances by potential of evaluating the brightness or sizes of gadgets interior the unknown galaxy with those in Earth’s galaxy. The brightest stars, supernovas, action picture star clusters, and gas clouds have been used for this purpose. Cepheid variables, stars the brightness of which varies periodically, are exceptionally efficient because of the fact the era of pulsation is with regards to the intrinsic brightness of the action picture star. by potential of observing periodicity, the genuine brightness could be computed and in comparison with the plain brightness; distance can then be inferred. Astronomers have discovered that the fee of the celebs as they orbit the middle of their galaxy relies upon on the intrinsic brightness and mass of that galaxy. at as quickly as rotating galaxies are fairly luminous; slowly rotating ones are intrinsically faint. If the orbital velocities of stars in a galaxy could be desperate, then the gap of that galaxy could be inferred.