ASTR 3 Lecture Notes - Lecture 9: Milky Way, Earth Mass, Circumstellar Habitable Zone
Document Summary
Avg dist a = 39. 4 au, but varies from ~29-49 au. Cold! b/c so far away (-238 to -218 c) Had a pluto fly-by last summer, got w/i 7800 m of pluto"s surface. Diameter is ~18% that of earth"s, charon ~half size of pluto. Ice-rich crust, geologically young surface regions, glacial flows. Atmospheric pressure is ~10 microbars (10^-5 that of earth"s) Now, ~2900 extrasolar planets known, ~2500 additional likely candidates. Majority have been found by rv or transit. The sun orbits the common center of mass (newton"s 3rd law equal and opposite force) Detect motion of the star using doppler shift (alternating blue and red shifts approaching and receding) Radial velocity curves tell you about mass and orbit of planet. Most planets detected w/ rv are massive (~jupiter-ish size or >) and close to the star (<1 au) These bigger planets make the largest/most rapid wobble, :. easiest to detect. Only practical for very faint stars and bright (hot) planets.
