UPPER MASS LIMITS FOR KNOWN RADIAL VELOCITY PLANETS FROM HIPPARCOS INTERMEDIATE ASTROMETRIC DATA

摘要

For all 104 extrasolar planetary candidates known today, we calculate the expected peak-to-peak astrometric signatures, using the spectroscopic elements, primary star masses and the Hipparcos parallaxes. For those eight stars with expected astrometric signatures larger than 1 mas, we fit an orbital model to the Hipparcos Intermediate Astrometric Data, using again the spectroscopic elements; the only two free parameters in the fit are thus the inclination and the ascending node. In no case the astrometric signature of the companion is detected in the Hipparcos Data. However, the non-detection of this astrometric signatures places stringent constraints on the upper mass limits of the companions; in all eight investigated cases the substellar nature of the companion could be established. The derived 3σ upper mass limits are: 15 M_J for υ And d, 16 M_J for 14 Her, 44 M_J for HD 38529 c, 20 M_J for HD 33636, 2.5 M_J for ε Eri, 43 M_J for HD 168443 c, 31 M_J for HD 39091, and 6.3 M_J for 55 Cnc d. Three of those systems have been investigated before by Zucker & Mazeh (2001), and our results for υ And d and 14 Her are in excellent agreement. The results for ε Eri differ by about an order of magnitude. Zucker & Mazeh (2001) used somewhat different orbital elements for ε Eri, but the effect is too large to be caused by differences in the orbital elements. We caution however that our results for ε Eri and especially 55 Cnc d are less reliable because their orbital periods exceed the time baseline covered by the Hipparcos measurements.