AST 2002 Chapter Notes - Chapter 10: Doppler Spectroscopy, Gravitational Lens, Orbital Period
Document Summary
Other stars are distant suns, they might be orbited by their own planets. Extrasolar planets- a planet orbiting a star other than our sun; lies beyond our solar system. Planets are extremely tiny compared to the vast distances between stars. Stars are typically a billion times brighter than the light reflected by any orbiting planet, so starlight tends to overwhelm any planetary light in photographs. The problems are lessened if we observe in infrared light. Planets emit their own infrared light and stars are dimmer in the infrared. There are two general ways of learning about a distant object: Directly: by obtaining images or spectra of the object. Observing the motion of a star to detect the subtle gravitational tugs of orbiting planets. O(cid:271)se(cid:396)(cid:448)i(cid:374)g (cid:272)ha(cid:374)ges to a sta(cid:396)"s (cid:271)(cid:396)ight(cid:374)ess that o(cid:272)(cid:272)u(cid:396) (cid:449)he(cid:374) o(cid:374)e of its planets passes in. Indirectly: by inferring the o(cid:271)je(cid:272)t"s e(cid:454)iste(cid:374)(cid:272)e o(cid:396) p(cid:396)ope(cid:396)ties (cid:449)ithout a(cid:272)tuall(cid:455) seei(cid:374)g it front of the star as viewed from earth.
