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arXiv 0908.1612astro-ph.EPastro-ph.SR
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凯克天文台发现两颗系外行星

Two Exoplanets Discovered at Keck Observatory

J. A. Valenti, D. A. Fischer, G. W. Marcy, J. A. Johnson, G. W. Henry, J. T. Wright, A. W. Howard, M. Giguere, H. Isaacson

摘要:

我们介绍了凯克天文台发现的两颗系外行星。HD 179079是一颗G5亚巨星,拥有一颗热的海王星行星,Msini = 27.5 M_地球,轨道为14.48 d,低偏心率。这颗行星引起的恒星反射速度的半振幅为K = 6.6 m/s。HD 73534是一颗G5亚巨星,其质量为1.1 Mjup,K = 16 m/s,轨道近似为圆形,周期为4.85年。这两颗恒星都是色球不活跃且富含金属的。我们讨论了一个已知的,经典的偏差在测量偏心率的轨道速度半幅值,K,可比的径向速度的不确定性。对于周期大于10天的系外行星,观测到的系外行星偏心率分布在大振幅系统(K > 80 m/s)中几乎是平坦的,但在低振幅系统(K > 20 m/s)中则向低偏心率方向线性上升。

英文摘要:

We present two exoplanets detected at Keck Observatory. HD 179079 is a G5 subgiant that hosts a hot Neptune planet with Msini = 27.5 M_earth in a 14.48 d, low-eccentricity orbit. The stellar reflex velocity induced by this planet has a semiamplitude of K = 6.6 m/s. HD 73534 is a G5 subgiant with a Jupiter-like planet of Msini = 1.1 M_jup and K = 16 m/s in a nearly circular 4.85 yr orbit. Both stars are chromospherically inactive and metal-rich. We discuss a known, classical bias in measuring eccentricities for orbits with velocity semiamplitudes, K, comparable to the radial velocity uncertainties. For exoplanets with periods longer than 10 days, the observed exoplanet eccentricity distribution is nearly flat for large amplitude systems (K > 80 m/s), but rises linearly toward low eccentricity for lower amplitude systems (K > 20 m/s).

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