High-precision radial-velocity measurement with a small telescope: Detection of the tau Bootis exoplanet

Abstract

The successful detection is reported of radial-velocity variations due to orbital motion of the substellar companion of the star tau Bootis, from data obtained with a small aperture (0.4m) telescope and a fibre-fed high-resolution spectrograph. Radial-velocity observations from observing runs in 2000 and 2004 reveal a periodic variation of 3.30 +/-0.02d, which is consistent with the previously determined value of 3.3125 +/-0.0002d. We fit our data to a circular orbit with the known period, and derive a velocity amplitude of 471 +/-10m s-1 (in agreement with the previously published value of 469 +/-5m s-1), and determine a time of maximum velocity (Tmax) of HJD 2453113.95 +/-0.01. These observations explore the minimum system requirements for precise radial-velocity measurements.