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.24-Aug-2015
How are variable stars measured?
You estimate the magnitude of a variable star with the help of a comparison star, using steps of 0.1 of a magnitude. So if your comparison star is mag. +10.3 and you think the variable is four-tenths brighter, you'd record it as '103 – 4'.
How do you find the distance to a Cepheid variable star?
0:462:20Determining Distances with Cepheid Variable Stars – YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd we put that information into our distance formula right. And those are that we get that ourMoreAnd we put that information into our distance formula right. And those are that we get that our Cepheid variable star is four point six nine times ten to the ninth astronomical units away.
How is distance measured in astronomy?
Astronomers measure the distance between objects in space using a tool called the 'cosmic distance ladder', which is a range of different interconnected techniques (see below).
How do astronomers find variable stars?
Amateur astronomers can do useful scientific study of variable stars by visually comparing the star with other stars within the same telescopic field of view of which the magnitudes are known and constant. By estimating the variable's magnitude and noting the time of observation a visual lightcurve can be constructed.
How do astronomers measure the distance to RR Lyrae stars?
RR Lyrae stars make it easy to determine the distance to another galaxy. Just measure the average apparent magnitude of the variables, and compare the known absolute magnitude. A typical RR Lyrae has a luminosity perhaps 50 times greater than the Sun.
Why can astronomers use Cepheid variables to determine 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.
How do astronomers measure the distance to a nearby star quizlet?
Astronomers often use parallax to measure distances to nearby stars. Parallax is the apparent change in position of an object when you look at it from different places.
How do astronomers measure the distance of galaxies?
Astronomers can use what are called surface brightness fluctuations (SBF, for short), along with the color of a galaxy, to calculate how far away it is from earth. Most galaxies measured in this way are millions of light years away.
What must be measured to determine distance by the Cepheid variable star method?
What must be measured to determine distance by the Cepheid variable star method? The apparent magnitude of the variable star. The period of pulsation of the variable star. With the 100-inch telescope, Harlow Shapley could not resolve variable stars in the more distant globular clusters of the Milky Way.