We discuss the discovery and characterization of the circumbinary planet Kepler-38b. The stellar binary is single-lined, with a period of 18.8?days, and consists of a moderately evolved main-sequence star (MA = 0.949 ± 0.059 M ☉ and RA = 1.757 ± 0.034 R ☉) paired with a low-mass star (MB = 0.249 ± 0.010 M ☉ and RB = 0.2724 ± 0.0053 R ☉) in a mildly eccentric (e = 0.103) orbit. A total of eight transits due to a circumbinary planet crossing the primary star were identified in the Kepler light curve (using Kepler Quarters 1-11), from which a planetary period of 105.595 ± 0.053 days can be established. A photometric dynamical model fit to the radial velocity curve and Kepler light curve yields a planetary radius of 4.35 ± 0.11 R ⊕, or equivalently 1.12 ± 0.03 R Nep. Since the planet is not sufficiently massive to observably alter the orbit of the binary from Keplerian motion, we can only place an upper limit on the mass of the planet of 122 M ⊕ (7.11 M Nep or equivalently 0.384 M Jup) at 95% confidence. This upper limit should decrease as more Kepler data become available.
展开▼
机译：我们讨论了环绕行星开普勒38b的发现和表征。恒星双星为单行，周期为18.8天，由适度演化的主序星（MA = 0.949±0.059 M☉和RA = 1.757±0.034 R☉）与低质量恒星配对（MB = 0.249±0.010 M☉和RB = 0.2724±0.0053 R☉）在一个偏心（e = 0.103）的轨道上。在开普勒光度曲线中（使用开普勒四分之一圈1-11），总共确定了8个因外行星穿过初恒星而发生的过渡，由此可以确定105.595±0.053天的行星周期。拟合径向速度曲线和开普勒光曲线的光度动力学模型产生的行星半径为4.35±0.11 R⊕或等效地为1.12±0.03 R Nep。由于行星的质量不足以观察到由开普勒运动引起的二元轨道的变化，因此我们只能以95％的置信度对122 M⊕（7.11 M Nep或等效地0.384 M Jup）的行星质量设置上限。随着更多的开普勒数据可用，该上限应减小。
展开▼
