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D. McDavitt, J. Ge, C. DeWitt, J. Bernecker, R. Mellon, S. Mahadevan, L. Ramsey, A. Wolszczan (Penn State), M. Rushford (LLNL)
An optical/infrared dispersive interferometer is being developed at Penn State for extra-solar planet searches at the Hobby-Eberly Telescope (HET). This instrument is a combination of a wide angle Michelson type interferometer and an intermediate resolution spectrograph (R \approx 15000). It is designed to provide very low instrument noise for sensitive Doppler radial velocity measurements aimed at detecting extra-solar planets with a velocity perturbation amplitude of a few m/s around nearby F, G, K and M dwarfs. It is a modified version of a prototype, developed by Jian Ge and his collaborators earlier at LLNL, with a much improved detection efficiency to allow observation of faint stars (V \approx 11 mag.) in the both optical and near-IR wavelengths. The prototype with R = 5600 has demonstrated a radial velocity precision of 7 m/s at the Lick 1 m telescope in 1999. New instrument components including an imaging slicer and an interferometer cavity control system are being developed and tested at Penn State. The image slicer is used to convert the telescope's circular beams to rectangular ones in order to increase the detection efficiency and also allow convenient placement of an interferometer fringe comb on stellar absorption lines for precision fringe phase measurements. The interferometer cavity control system is used to reduce systematic errors and also control phase shifts. Reference sources other than iodine absorption are being studied for calibrating the new instrument at red and near-IR wavelengths. The instrument's first light at the HET will be spring 2001. Simulations of the instrument's performance show that a Doppler radial velocity precision of 1 m/s can be achieved for a late type star with a S/N of 200, a wavelength coverage of 500 Å\ at 1.55 \mum and R = 15000.
The development of the instrument is supported by the Penn State Eberly College of Sciences.
The author(s) of this abstract have provided an email address for comments about the abstract: jian@astro.psu.edu