In recent years astronomers have observed over 1,000 stars that are thought to contain planetary systems akin to our own solar system, and new discoveries are rapidly being added. In order to confirm and characterize these systems, it is necessary to conduct numerous observations of the host stars. Telescopes collect the light from the star and pass it through a spectrograph that spreads the light out into a rainbow-like "spectrum" that can be analyzed to determine the velocity of the star as viewed from earth. If the observed velocity varies in a repeatable way it may be due to the presence of a companion object in orbit around the star. These observations require a considerable amount of telescope time and there is a shortage of the kinds of telescopes and spectrographs specifically designed to do this high precision work. This is especially problematic for so-called short period orbits, where the orbiting planet is close to its host star and the planetary "year" (the time for a full orbit around the host star) may be days or even hours. To determine the orbital characteristics of these objects frequent observations around the clock are required. As the earth rotates on its axis, however, stars, just like the sun and moon, set in the west, so they can only be seen for a few hours from a given observatory. Dr. Timothy Brown of the Las Cumbres Observatory Global Telescope network proposes to put identical spectrographs on several telescopes around the earth so that the stars can be monitored continuously as the earth turns. He and his team have designed a high resolution and very precise spectrograph and they will build six copies. Observations made with this network of spectrographs is certain to add considerably to our understanding of planetary systems. This work is funded by NSF's Division of Astronomical Sciences through the Major Research Instrumentation program.
