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Paper: Modulation of Ca II H and K Emission by Short-Period Planets
Volume: 294, Scientific Frontiers in Research on Extrasolar Planets
Page: 157
Authors: Shkolnik, E.; Walker, G. A. H.; Bohlender, D. A.
Abstract: We have detected modulation of the Ca II H and 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-angstrom variation at about the 1% level and (2) changes on a scale of 0.5-angstroms (about 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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