The CORALIE survey for southern extra-solar planets VII - Two short-period Saturnian companions to HD 108147 and HD 168746
The CORALIE survey for southern extra-solar planets VII - Two short-period Saturnian companions to HD 108147 and HD 168746
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CORALIE 南系外行星巡天 VII - HD 108147 和 HD 168746 的两颗短周期土星伴星
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发表时间：
2002
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通讯作者：
M. Burnet
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作者：
F. Pepe;M. Mayor;F. Galland;D. Naef;D. Queloz;N. Santos;S. Udry;M. Burnet
接收日期2002年2月7日/接受日期2002年3月19日我们发现了HD 108147和HD 168746的两个土星质量伴星。这两颗行星都属于迄今为止发现的最轻的行星。HD 168746的最小质量只有土星质量的0.77倍，轨道周期为6.4天。HD 108147的伴星绕母星星公转一周需要10.9天，其最小质量是土星的1.34倍。它的轨道特征是高离心率，e = 0.50，表明可能存在第二个伴星。利用多普勒技术探测土星质量行星，对径向速度测量精度要求很高。这两个新的候选者是通过CORALIE阶梯光栅摄谱仪发现的。CORALIE的仪器精度与同时ThAr参考技术相结合，已达到优于3 m s - 1的水平。在许多观测对象上，精度现在受到光子噪声的限制。本文提出了加权互相关技术，该技术可以改善计算径向速度的光子噪声。我们还讨论了修改的数值互相关掩模，显着减少了残留的扰动效应所产生的大地吸收线。
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, e = 0.50, 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.