Hybrid system will search for planets with a mass near that of Earth
Arsen Hajian and Tyler Nordgren of the US Naval Observatory (Washington, DC) coupled a Fourier transform spectrometer (FTS) with a spectrograph to produce an instrument designed to measure the subtle motion of stars caused by orbiting planets of near-Earth mass. The hybrid multichannel FTS combines the velocity precision of the first instrument with the sensitivity to faint sources characteristic of the second. It should provide velocity precision near 30 cm/s, compared to the 3 m/s common with conventional planet-hunting spectrometers, and will not be limited to observing very bright sources such as the Sun.
Required equipment, including the spectrometer, spectrograph, optics for variable delay paths, and laser system are components of the Navy Prototype Optical Interferometer, an array of telescopes being built by the US Naval Observatory, the Naval Research Laboratory (Washington, DC), and Lowell Observatory (Flagstaff, AZ). According to the astronomers, preliminary observations of Betelgeuse confirm theoretical predictions of the prototype, even though it used a collecting area only 12 cm in diameter and was thus not sensitive enough to detect Earth-size planets, something the astronomers believe would be possible with a 3-m-diameter telescope.