The On/Off Nature of Star-Planet Interactions
The On/Off Nature of Star-Planet Interactions
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DOI：
10.1086/527351
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
E. Shkolnik;D. Bohlender;G. Walker;A. Collier Cameron
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文献类型：
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作者：
E. Shkolnik;D. Bohlender;G. Walker;A. Collier Cameron
有证据表明，一颗星星和它的热木星之间存在着可观测到的磁相互作用，这似乎是恒星活动与行星轨道同步的周期性变化。在这项研究中，我们使用几个恒星活动指标监测色球活动的七颗恒星的热闪烁，使用新的高分辨率阶梯光谱与ESPaDOnS收集的几个晚上在2005年和2006年从CFHT（Ca II H λ3968，K λ3933，Ca II红外三线[IRT] λ8662线，Hα λ6563，和He I λ5876）。HD 179949的Ca II H和K发射与其行星轨道的同步性在六个历元中的四个历元中清晰可见，而在其他两个季节中，Prot = 7天的旋转调制是明显的。我们观察到一个类似的现象，在太阳和。这两个系统中恒星-行星相互作用（SPI）的开/关性质可能是整个活动周期中不断变化的恒星磁场结构的函数。凌日系统HD 189733的变化可能与一个随星星旋转的活跃区域有关;然而，超过旋转调制的耀斑可能与它的热木星有关。至于HD 179949，HD 189733和τ Boo的平均绝对偏差（MAD）测量的峰值变化都领先亚行星经度约70°。这种活动与Mpsin i与行星自转周期之比（与热木星的磁矩成比例的量）之间的初步相关性仍然是可行的，这是由史考尼克及其同事首次提出的。这项工作进一步表征SPI，提高其作为太阳系外行星磁场探测器的潜力。
Evidence suggesting an observable magnetic interaction between a star and its hot Jupiter appears as a cyclic variation of stellar activity synchronized to the planet's orbit. In this study we monitored the chromospheric activity using several stellar activity indicators of seven stars with hot Jupiters using new high-resolution echelle spectra collected with ESPaDOnS over a few nights in 2005 and 2006 from the CFHT (Ca II H λ3968, K λ3933, the Ca II infrared triplet [IRT] λ8662 line, Hα λ6563, and He I λ5876). Synchronicity of the Ca II H and K emission of HD 179949 with its planet's orbit is clearly seen in four out of six epochs, while rotational modulation with Prot = 7 days is apparent in the other two seasons. We observe a similar phenomenon on υ And. This on/off nature of star-planet interaction (SPI) in the two systems is likely a function of the changing stellar magnetic field structure throughout its activity cycle. Variability in the transiting system HD 189733 is likely associated with an active region rotating with the star; however, the flaring in excess of the rotational modulation may be associated with its hot Jupiter. As for HD 179949, the peak variability as measured by the mean absolute deviation (MAD) for both HD 189733 and τ Boo leads the subplanetary longitude by ~70°. The tentative correlation between this activity and the ratio of Mpsin i to the planet's rotation period, a quantity proportional to the hot Jupiter's magnetic moment, first presented by Shkolnik and coworkers remains viable. This work furthers the characterization of SPI, improving its potential as a probe of extrasolar planetary magnetic fields.