* Astronomy

Title: A Massive Planet to the Young Disc Star HD 81040
Authors: A. Sozzetti (1,2), S. Udry (3), S. Zucker (4), G. Torres (1), J. L. Beuzit (5), D. W. Latham (1), M. Mayor (3), T. Mazeh (4), D. Naef (6), C. Perrier (5), D. Queloz (3), J.-P. Sivan (7) ((1) Harvard-Smithsonian Center for Astrophysics, (2) INAF-Osservatorio Astronomico di Torino, (3) Geneva Observatory, (4) Tel Aviv University, (5) Laboratoire d'Astrophysique de Grenoble, (6) European Southern Observatory, (7) Observatoire de Haute-Provence)


Researchers report the discovery of a massive planetary companion orbiting 1.94 AU from the young (0.7 billion years) disc G2/G3 star HD 81040. Based on five years of precise radial-velocity measurements with the HIRES and ELODIE spectrographs, they derive a spectroscopic orbit with a period P =1001.7 ±7.0 days and eccentricity e = 0.526 ±0.042. The inferred minimum mass for the companion of m2\sin i = 6.86 ±0.71 Jupiter masses places it in the high-mass tail of the extrasolar planet mass distribution.


Radial-velocity measurements as a function of time for HD 81040. Open circles identify Keck/HIRES velocities, while filled black circles correspond to the ELODIE dataset.

The radial-velocity residuals exhibit a scatter significantly larger than the typical internal measurement precision of the instruments. Based on an analysis of the Ca II H and K line cores, this is interpreted as an activity-induced phenomenon.
However, they find no evidence for the period and magnitude of the radial-velocity variations to be caused by stellar surface activity. The observed orbital motion of HD81040 (HIP 46076, BD+20.2314) is thus best explained with the presence of a massive giant planet companion.


Position(2000): RA= 09 23 47.09 Dec= +20 21 52.0
Area Size 12'9 x 12'9

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