PHYSICS 20E Lecture Notes - Lecture 21: 51 Pegasi, Solar Radius, Orbital Speed
Document Summary
Want rocky planets, like the size of earth. Find them in the habitable zone, region around their star that allows to have liquid water. Kepler telescope helped discover many new planets. Two most common methods for detecting planets: radial velocity wobble of host star, the transit dimming of host star. Planets and stars orbit each other about their common center of mass. The parent star orbits closer to the center of mass because it has more pass. The star"s orbital speed is smaller, in proportion to the planet-to-star mass ratio. The radial velocity ( wobble ) method looks for orbital motions using doppler effect. Measuring the orbital speed and period gives an estimate of the unseen planet"s mass. Wobble speed of the host star is very small and thus challenging to measure. Need to measure speeds with extremely high precision. In 1995, 51 pegasi became the first sun-like star with a planet detected by the rv method.
