Searching for star–planet interactions within the magnetosphere of HD 189733
Searching for star–planet interactions within the magnetosphere of HD 189733
复制标题
寻找 HD 189733 磁层内恒星与行星的相互作用
DOI：
10.1111/j.1365-2966.2010.16715.x
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发表时间：
2010
影响因子：
4.8
通讯作者：
A. C. Cameron
中科院分区：
文献类型：
--
作者：
R. Fares;J. Donati;C. Moutou;M. Jardine;J. Grießmeier;P. Zarka;E. Shkolnik;D. Bohlender;C. Català;A. C. Cameron
HD 189733 是一颗 K2 矮星，由一颗半径为 8.8 颗恒星的巨行星围绕其运行。为了研究恒星与行星之间的磁层相互作用，我们探索了主恒星的大尺度磁场和活动。
在两次监测活动（2007 年 6 月和 2008 年 7 月）期间，我们使用安装在 3.6 米加拿大-法国-夏威夷望远镜和位于 Pic du Midi 的 2 米伯纳德·利奥特望远镜上的 ESPaDOnS 和 NARVAL 分光偏振计收集了光谱。
HD 189733 的表面磁场主要为环形，强度高达 40 G。这颗恒星正在差动旋转，纬向角速度切变为 dΩ= 0.146 ± 0.049 rad d−1，对应的赤道周期和极周期分别为 11.94 ± 0.16 d 和 16.53 ± 2.43 d。对恒星活动的研究表明，它主要受恒星自转（而不是轨道周期或恒星自转与轨道周期之间的拍频周期）的调节。我们没有报告恒星和行星之间磁层相互作用的明确证据。
我们还推断了恒星日冕中的场，并根据重建的场拓扑计算了 HD 189733b 预期的行星无线电发射。我们在此模型框架中预测的无线电通量是随时间变化的，并且可以通过 LOFAR 检测到。
HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star.
We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada–France–Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (2007 June and 2008 July).
HD 189733 has a mainly toroidal surface magnetic field, having a strength that reaches up to 40 G. The star is differentially rotating, with latitudinal angular velocity shear of dΩ= 0.146 ± 0.049 rad d−1, corresponding to equatorial and polar periods of 11.94 ± 0.16 d and 16.53 ± 2.43 d, respectively. The study of the stellar activity shows that it is modulated mainly by the stellar rotation (rather than by the orbital period or the beat period between the stellar rotation and the orbital periods). We report no clear evidence of magnetospheric interactions between the star and the planet.
We also extrapolated the field in the stellar corona and calculated the planetary radio emission expected for HD 189733b, given the reconstructed field topology. The radio flux we predict in the framework of this model is time variable and potentially detectable with LOFAR.