A new interferometric study of four exoplanet host stars: θ Cygni, 14 Andromedae, υ Andromedae and 42 Draconis
A new interferometric study of four exoplanet host stars: θ Cygni, 14 Andromedae, υ Andromedae and 42 Draconis
复制标题
DOI：
10.1051/0004-6361/201219467
复制
发表时间：
2012-08
影响因子：
6.5
通讯作者：
R. Ligi;D. Mourard;A. Lagrange;K. Perraut;T. Boyajian;P. B'erio;N. Nardetto;I. Tallon-Bosc;H. Mcalister;T. Brummelaar;S. Ridgway;J. Sturmann;L. Sturmann;N. Turner;C. Farrington;P. J. Goldfinger
中科院分区：
文献类型：
--
作者：
R. Ligi;D. Mourard;A. Lagrange;K. Perraut;T. Boyajian;P. B'erio;N. Nardetto;I. Tallon-Bosc;H. Mcalister;T. Brummelaar;S. Ridgway;J. Sturmann;L. Sturmann;N. Turner;C. Farrington;P. J. Goldfinger
上下文自从1995年第一颗围绕太阳型星星运行的系外行星被发现以来，人们对系外行星系统的兴趣不断增加。研究系外行星的宿主恒星对于建立围绕各种类型恒星的系外行星之间的联系以及了解恒星和系外行星各自的演化至关重要。目标。利用干涉测量数据得到的边缘变暗直径（LDD），我们确定了四颗系外行星宿主星的基本参数。我们对F4主序星星星天鹅座θ星特别感兴趣，开普勒望远镜最近揭示了这类星星的类太阳振荡。此外，最近使用SOPHIE和OHP的光度和光谱测量显示了150天的准周期径向速度的证据。这种径向速度周期性变化的模型预测要么是一个复杂的行星系统围绕着星星运行，要么是一个新的、未经确认的恒星脉动模式。方法.我们用VEGA/CHARA（威尔逊山，加州）在几个三望远镜配置中对天鹅座θ、仙女座14、仙女座14和天龙座42进行了两年的干涉观测。我们测量了精确的肢体变暗的直径，并根据经验定律推导出它们的半径、质量和温度。结果我们获得了14 And、42 Dra和42 Dra星的新的精确基本参数。我们还获得了最小精度为1.3%的边缘暗化直径，导致14 And B、16 And B和42 Dra B的最小行星质量分别为M sini = 5.33 ± 0.57、0.62 ± 0.09和3.79 ± 0.29 MJup。θ Cyg的干涉测量显示了至今仍无法解释的显著的直径变化。我们建议，这些差异的干涉数据的存在是由一个内在的变化的星星或一个未知的密切的同伴围绕它运行。
Context. Since the discovery of the first exoplanet in 1995 around a solar-type star, the interest in exoplanetary systems has kept increasing. Studying exoplanet host stars is of the utmost importance to establish the link between the presence of exoplanets around various types of stars and to understand the respective evolution of stars and exoplanets. Aims. Using the limb-darkened diameter (LDD) obtained from interferometric data, we determine the fundamental parameters of four exoplanet host stars. We are particularly interested in the F4 main-sequence star, θ Cyg, for which Kepler has recently revealed solar-like oscillations that are unexpected for this type of star. Furthermore, recent photometric and spectroscopic measurements with SOPHIE and ELODIE (OHP) show evidence of a quasi-periodic radial velocity of ∼150 days. Models of this periodic change in radial velocity predict either a complex planetary system orbiting the star, or a new and unidentified stellar pulsation mode. Methods. We performed interferometric observations of θ Cyg, 14 Andromedae, υ Andromedae and 42 Draconis for two years with VEGA/CHARA (Mount Wilson, California) in several three-telescope configurations. We measured accurate limb darkened diameters and derived their radius, mass and temperature using empirical laws. Results. We obtain new accurate fundamental parameters for stars 14 And, υ And and 42 Dra. We also obtained limb darkened diameters with a minimum precision of ∼1.3%, leading to minimum planet masses of M sini = 5.33 ± 0.57, 0.62 ± 0.09 and 3.79 ± 0.29 MJup for 14 And b, υ And b and 42 Dra b, respectively. The interferometric measurements of θ Cyg show a significant diameter variability that remains unexplained up to now. We propose that the presence of these discrepancies in the interferometric data is caused either by an intrinsic variation of the star or an unknown close companion orbiting around it.