Issue |
A&A
Volume 388, Number 2, June III 2002
|
|
---|---|---|
Page(s) | 632 - 638 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20020433 | |
Published online | 31 May 2002 |
The CORALIE survey for southern extra-solar planets VII*
Two short-period Saturnian companions to HD 108147 and HD 168746
Observatoire de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
Corresponding author: F. Pepe, Francesco.Pepe@obs.unige.ch
Received:
7
February
2002
Accepted:
19
March
2002
We present the discovery of two Saturn-mass companions to HD 108147 and HD 168746. Both belong to the lightest ever discovered planets. The minimum mass of the companion to HD 168746 is of only 0.77 the mass of Saturn and its orbital period is 6.4 days. The companion to HD 108147 orbits its parent star in 10.9 days and its minimum mass is 1.34 that of Saturn. Its orbit is characterized by a high eccentricity, , indicating possibly the presence of a second companion.
The detection of Saturn-mass planets by means of the Doppler technique demands high
radial-velocity measurement precision. The two
new candidates were discovered by means of the CORALIE
echelle spectrograph. The instrumental accuracy of CORALIE
combined with the simultaneous ThAr-reference technique has reached a level
better than 3 m s-1. On many observed objects the precision is now limited by
photon noise. We present in this paper the weighted cross-correlation technique,
which leads to an improvement in the photon noise of the computed radial velocity.
We discuss as well a modification of the numerical cross-correlation mask which
reduces significantly the residual perturbation effects produced by telluric absorption
lines.
Key words: techniques: radial velocities / stars: individual: HD 108147 / stars: individual: HD 168746 / stars: planetary systems
© ESO, 2002
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