Astrophysics Final '25 Exam questions and answers

Astrophysics Final '25 Exam questions and answers How do the Balmer and Lyman line series form in the hydrogen spectrum? Balmer lines form when electrons transition from higher levels down to the n=2 energy level, producing visible-light emission. Lyman lines form when electrons fall to the n=1 level, producing ultraviolet emission. What is the Doppler effect? Give one example in astronomy. The Doppler effect is the change in observed wavelength due to the motion of a source toward or away from the observer. In astronomy, it is used to measure stellar radial velocities by observing shifts in spectral lines. This method is also key to detecting exoplanets via the star's "wobble." How do we measure stellar masses? We can measure the masses of stars in binary star systems using orbital motions and Newton's version of Kepler's third law if we know the orbital period and separation of the two stars. What is an ellipse? An ellipse is a closed geometric curve with two foci where the sum of distances from any point on the curve to the two foci is constant. Planets follow elliptical orbi