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Modulation of Ca II H & K Emission by Short-Period Planets

Evgenya Shkolnik·Gordon A. H. Walker·David A. Bohlender
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Abstract

We have detected modulation of the Ca II H&K reversal structure in four out of five 51 Peg-type stars whose planets have orbital periods between 3 and 4 days. We observe two effects in the K-core: (1) a broad 3-A variation at ~1% level and (2) changes on a scale of 0.5 A (~1-3%) in each of the three reversal features. The nightly variations are coherent in both H and K. From differential radial velocities measured to better than 20 m/s, up-to-date phases were extracted. The enhancements in the reversals tend to be greatest at the sub-planetary points which may imply that there is a magnetic interaction between the star's outer layers and the magnetosphere of the planet. These high-S/N (500 per pixel in the continuum) and high-resolution (R = 110,000) data are too few to confirm orbital synchronization.

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Evgenya Shkolnik, Gordon A. H. Walker, David A. Bohlender. 2002-09-02. Modulation of Ca II H & K Emission by Short-Period Planets. https://arxiv.org/abs/astro-ph/0209014

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