AST 2002 Lecture Notes - Lecture 27: Exoplanet, Orbital Period, Minute And Second Of Arc
Document Summary
Other planetary systems: the new science of distant worlds. A sun-like star is about a billion times brighter than the light reflected from its planets; makes it difficult to detect. Planets are close to their stars, relative to the distance from us to the star. Direct: pictures or spectra of the planets themselves. Indirect: measurements of stellar properties revealing the effects of orbiting planets. The sun and jupiter orbit around their common center of mass. The sun therefore wobbles around that center of mass with the same period as jupiter. Stars pull on planets, planets pull on stars. The su(cid:374)"s (cid:373)otio(cid:374) arou(cid:374)d the solar syste(cid:373)"s (cid:272)e(cid:374)ter of (cid:373)ass depends on tugs from all the planets. Astronomers around other stars that measured this motion could determine the masses and orbits of all the planets. The most massive planets cause the most wobbling. We can detect planets by measuring the (cid:272)ha(cid:374)ge i(cid:374) star"s positio(cid:374) o(cid:374) sky.
