Chapter 2, Problem 5DQ

The a star system contains two stars, one with apparent magnitude m = 10.5 and the other with m = 10.9. What is the combined apparent magnitude of the two stars?

As we read in the book, a star that appears to be 1 magnitude brighter will have approximately 2.5 times as much flux hitting an observer's detector/telescope/eye (i.e. a star with an apparent magnitude of 4 has approximately 2.5 times more flux hitting the detector as a star with an apparent magnitude of 5). With this in mind what is the approximate ratio of the flux hitting the a detector for a star with an apparent magnitude of 3 compared to a star with an apparent magnitude of 7? (hint: remember that magnitudes follow a logarithmic scale, not a linear one)

The spectrum of a typical star shows absorption lines at different wavelengths than their laboratory values. If the observed wavelength is less than its laboratory value of 656.3 nm, one can conclude that...   A. The separation between Earth and the star is decreasing.   B. The separation between Earth and the star is increasing.   C. The separation between Earth and the star is unchanging   D. No conclusion is possible.