If an astronomer wants to find the distance to a star that is not variable and is located too far away for parallax measurements, she can:
A) use the star's light curve
B) find the star's luminosity class from its spectrum and read the luminosity from an H-R diagram
C) use Kepler's laws as modified by Newton
D) search for planets around the star since it is much easier to get the distance to planets
E) only throw up her hands in desperation; there is no way to even estimate the distance to such a star

Question

Quizplus · Accepted Answer

By finding the star's luminosity class from its spectrum and reading the luminosity from an H-R diagram, the astronomer can determine the star's intrinsic brightness. With the apparent brightness, which can be measured, the astronomer can use the inverse square law to calculate the distance to the star.

If an Astronomer Wants to Find the Distance to a Star