Unformatted text preview: on the size of the orbit; the orbit could be bigger than what I detect. Similarly, if I observe with just the Doppler method I am also finding just a lower bound on the size of the orbit. This means when I use these methods to find the mass of the invisible companion, I am really finding a lower bound. The mass could be what I calculate, or it could be larger. Both the wobble methods (astrometry and Doppler) are easier to observe if the mass of the invisible companion is larger. Hence they are, you might say, prejudiced against smaller masses. If we don't see many smaller masses it's not so much that they are not there, but that our system of detection doesn't find them as easily. The wobble methods are also prejudiced in favor of planets that are close to their stars, since the gravitational force, which produces the wobble, is greater if the planet is closer. The gravitational lensing method (below) however, works the other way....
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- Fall '10