AST 2002 Lecture Notes - Lecture 28: Orbital Period, Planetary Migration
Document Summary
We cannot measure an exact mass for a planet without knowing the tilt of its orbit, because doppler shift tells us only the velocity toward or away from us. Doppler data give us lower limits on masses. Suppose you found a star with the same mass as the sun moving back and forth with a period of 16 months it has a planet orbiting at greater than 1 au. The periods a(cid:374)d sizes of kepler 11"s 6 k(cid:374)o(cid:449)(cid:374) pla(cid:374)ets (cid:272)a(cid:374) (cid:271)e deter(cid:373)i(cid:374)ed usi(cid:374)g tra(cid:374)sit data. Most of the dete(cid:272)ted pla(cid:374)ets ha(cid:448)e or(cid:271)its s(cid:373)aller tha(cid:374) jupiter"s. Planets at greater distances are harder to detect with the current techniques. Orbits of some extrasolar planets are much more elongated (have a greater eccentricity) than those in our solar system. 2/3 of extrasolar planets were found by kepler. Results from kepler indicate that planets are common, and small planets greatly outnumber large planets. Some extrasolar planets have highly elliptical orbits.
