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.Comment: 4 pages, 2 figures, in newpasp.sty format. To be published by PASP
(ed. Drake Deming) in the proceedings of the conference entitled "Scientific
Frontiers in Research on Extrasolar Planets," held at the Carnegie
Institution of Washington, DC, June 18-21, 200