Understanding and reducing dispersed fixed-delay interferometric data for extrasolar planet searches

2007 • 2007PhDT........62V

Authors • van Eyken, Julian Christopher

Abstract • The dispersed fixed-delay interferometer represents a new instrument concept for high-precision radial velocity surveys for extrasolar planets. A combination of an interferometer in series with a medium resolution spectrograph, it has the potential for performing multi-object surveying down to faint magnitude limits, where previous radial velocity techniques have been limited to observing only one target at at time. The sample of relatively bright stars that can quickly be surveyed using traditional radial velocity techniques with current technology is becoming exhausted, and the radial-velocity planet discovery rate is beginning to level out. Because of the large sample of extrasolar planets needed to perform statistical analyses to be able to understand aspects of planetary formation and evolution, such a multi-object instrument represents the next logical step in instrumentation for extrasolar planet research. As a useful by-product, the instrument has the potential to provide simple measurements of the projected rotational velocities of stars. The development of this instrument has necessitated the development of new data reduction procedures to efficiently and reliably turn the raw data into meaningful results, and a careful consideration of precision levels and sources of error. This in turn has required fleshing out a detailed understanding of the physical principles of the instrument. The single-object Exoplanet Tracker installed at Kitt Peak National Observatory and the multi-object W. M. Keck Exoplanet-Tracker at Apache Point Observatory are the first two fully-fledged astronomical radial velocity instruments to have been built based on this new technique. The former served to prove the concept with a successful confirmation of the known planet, 51 Peg b. We were later able to use it to discover a new planet, HD 102195 b, or ET-1. The latter has also demonstrated detection of known planets, and has been the workhorse for a pilot survey in preparation for a planned major wide-field survey over the next decade.

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