Dr. Douglas Caldwell

A decade ago, astronomers could only speculate about whether planets were a happy commonplace in the universe, or distressingly rare. The discovery of hundreds of worlds around other stars has shown that planets orbit at least 5 to 10 percent of all stars. But how many of these planets are Earth-size, and possibly Earth-like?

Physicist Doug Caldwell is an expert on one of the most promising schemes for finding small worlds far beyond our solar system: looking for the slight dimming of a star caused when a planet crosses between it and us. Doug is involved in a trio of transit experiments, including one running at the South Pole. While admittedly a tough environment for an observatory, this antipodal location offers long nights and high altitude, perfect conditions for finding the small dip in stellar brightness that would betray a planet. In addition, Doug is also the Instrument Scientist for NASA’s Kepler Mission, an ambitious, space borne telescope that will examine one hundred thousand stars for evidence of orbiting worlds. If Earth-size planets are common, Doug Caldwell will be among the first to know.

Projects

“A Search for Extrasolar Planets from the South Pole”

NSF OPP–0126313

This project proposes to operate a small optical telescope at the South Pole to search for and characterize extrasolar planets. The method is to observe thousands of stars by continuously following a southern Galactic star filed with a CCD photometer, searching for the periodic dimming that occurs as a planet transits its parent star.The South Pole is the best place on the surface of the Earth to detect such planets because of the long winter night, during which randomly-phased transits can most efficiently be detected. Also, the constant altitude of a stellar field at the Pole avoids large daily atmospheric extinction variations allowing for higher photometric precision and a search for smaller planets. This project will increase tenfold the number of extrasolar planets for which transits are observed. Then, in conjunction with follow-on measurements from existing Southern Hemisphere Doppler velocity programs, planet densities can be determined. These data will provide information vital to theoretical models of planetary structure and formation.