Cool Stars 14 - Submitted Abstract # 252
This version created on 05 October 2006

Possible Detection of Planet-induced X-ray Emission in the HD 179949
System


Steven Saar, Smithsonian Astrophysical Obs.
Vinay Kashyap, Smithsonian Astrophysical Obs.
Manfred Cuntz, Univ. of Texas, Arlington
Evgenya Shkolnik, Univ. of Hawaii at Manoa
Jeffrey Hall, Lowell Obs.

We report on follow-up X-ray observations of the HD 179949 system with
Chandra/ACIS-S.  A close-in giant planet has been detected around this
F9 star, and ground-based observations show enhancements in Ca II HK
in phase with the planetary orbit (Porb~3d).  In order to mimimize the
confusion of planet-induced stellar activity enhancements with
underlying stellar variability, the X-ray observations were carried
out at nearly fixed stellar rotational phase (assuming Prot~9d), for a
variety of planetary orbital phases.  We find an ~30% increase in the
X-ray flux over quiescent levels coincident with the phase of the Ca
II enhancements.  There is also a trend for the emission to be hotter
at increased fluxes, confirmed by modeling (which shows the
enhancement at ~1 keV compared with ~0.4 keV for the background star).
We discuss the energetics of the phemonenon, and the additional
emission near phase 0.5.

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