19.9 Review Questions

Explain how parallax measurements can be used to determine distances to stars. Why can we not make accurate measurements of parallax beyond a certain distance?

Suppose you have discovered a new cepheid variable star. What steps would you take to determine its distance?

Explain how you would use the spectrum of a star to estimate its distance.

Which method would you use to obtain the distance to each of the following?

1. An asteroid crossing Earth’s orbit
2. A star astronomers believe to be no more than 50 light-years from the Sun
3. A tight group of stars in the Milky Way Galaxy that includes a significant number of variable stars
4. A star that is not variable but for which you can obtain a clearly defined spectrum

What are the luminosity class and spectral type of a star with an effective temperature of 5000 K and a luminosity of 100 L_Sun?