Search for Exoplanets
Alan P. Boss, Alycia J. Weinberger (DTM)
Guillem Anglada-Escude (University of Goettingen)
Rafael Brahm (PUC, Chile)
George Gatewood (Allegheny Observatory)
Steven Majewski, Richard Patterson (University of Virginia)
Ian Thompson (Carnegie Observatories)
Astrometric Planet Search on the du Pont Telescope
We have undertaken a new search for Jupiter-like planets in orbit around nearby stars. Using the 2.5-m du Pont telescope located at Carnegie's Las Campanas Observatory in Chile, we are searching for gas giant planets similar to Jupiter by the astrometric method. In this method, the wobble of the host star's position on the sky as it orbits around the center of mass of the star-planet system is measured with high accuracy. Knowing the mass of the star then allows the true mass of the planet, as well as its orbital parameters (including the semi-major axis, eccentricity, and inclination), to be determined. Our observations of the M7 cluster with the Tek5 camera on the du Pont imply that astrometric accuracies of 0.25 milliarcsec per hour may be achievable, sufficient to detect a Solar System analogue at 5 pc with a signal-to-noise ratio of 4.
We have built a specialized astrometric camera, the Carnegie Astrometric Planet Search (CAPS) camera, with support from the NSF and CIW. The heart of the CAPS camera is a Teledyne Hawaii-2RG HyViSI array, with the camera's design being optimized for high accuracy astrometry of red dwarf stars. Our preliminary estimate of the accuracy achieved with CAPSCam supports the M7 cluster estimate, at least for a single night of data. We will follow 100 nearby low mass stars, principally late M, L, and T dwarfs, for 10 years or more, in order to detect Jupiter-mass planets with orbital periods long enough to permit the existence of habitable, Earth-like planets on shorter-period orbits. Synthesis of organic materials and potential habitats for life beneath the Earth's land surface and seafloor, on other bodies in the solar system, and on extrasolar planets.
As part of this program, Carnegie scientists are analyzing organic chemical synthesis in water-rock systems under varying conditions of temperature, pressure, and chemistry to mimic environments that may be encountered in terrestrial and extraterrestrial settings. In related work, Carnegie scientists are investigating the physical and chemical environments of circumstellar disks around young stars and the nature of early organic compounds in extraterrestrial materials, such as meteorites.
Teledyne's (Rockwell Scientific) 2048 x 2048 HAWAII-2RG is the state of-the-art multiplexer for advanced astronomy and space telescope applications. Providing the ability to choose detector material (HgCdTe or Silicon PIN) allows the user access to any band from 350 nm to 5.3 micron. Selectable number of outputs (1, 4 or 32) and userselectable scan directions provide complete flexibility in data acquisition. The "Guide Mode" provides a programmable window which may be read out continuously at up to 5MHz pixel rate for stable tracking of guide stars. The readout is designed to allow interleaved readout of the guide window and the full frame science data. The Hawaii-2RG HyViSI array thus allows relatively bright target stars to be read out at a much higher cadence than the relatively faint reference stars.