Edward James Kennelly

A Planet Orbiting the Star ρ Coronae Borealis

We report the discovery of near-sinusoidal radial velocity variations of the G0V star ρ CrB, with period 39.6 days and amplitude 67 m s-1. These variations are consistent with the existence of an orbital companion in a circular orbit. Adopting a mass of 1.0 M☉ for the primary, the companion has minimum mass about 1.1 Jupiter masses and orbital radius about 0.23 AU. Such an orbital radius is too large for tidal circularization of an initially eccentric orbit during the lifetime of the star, and hence we suggest that the low eccentricity is primordial, as would be expected for a planet formed in a dissipative circumstellar disk.

A Radial Velocity Search for p-Mode Pulsations in η Bootis

The subgiant η Boo (G5 IV) has been reported to show p-mode pulsations, as evidenced by variations in the equivalent width of its hydrogen Balmer lines (reported by Kjeldsen et al.). In an attempt to confirm this report, we observed η Boos radial velocity with the AFOE spectrograph for a total of 22 hours spread over seven successive nights in 1995 March. We find no evidence for the presence of excess power at the frequencies reported by Kjeldsen et al.; our upper limit corresponds to typical mode amplitudes of 0.5 m s-1, about 3 times smaller than the velocity amplitudes they inferred. Signals with amplitudes larger than 0.5 m s-1 may be present at other frequencies within the 0-1000 μHz range, but evidence for such signals is scanty, and typical mode amplitudes greater than 1.5 m s-1 are clearly inconsistent with our observations.

The Oscillations of Tau Pegasi

We present extensive spectroscopic time series observations of the multiperiodic, rapidly rotating, ? Scuti star ? Pegasi. Information about the oscillations is contained within the patterns of line-profile variation of the stars blended absorption-line spectrum. We introduce the new technique of Doppler deconvolution with which to extract these patterns by modeling the intrinsic stellar spectrum and the broadening functions for each spectrum in the time series. Frequencies and modes of oscillation are identified from the variations using the technique of Fourier-Doppler imaging and a two-dimensional least-squares cleaning algorithm. We find a rich mode spectrum with degrees up to l = 20 and with frequencies below about 35 cycles day-1. Those modes with the largest amplitudes have frequencies that lie within a narrow band. We conclude that the observed spectrum can be explained if the modes of ? Peg propagate in the prograde direction with l |m| and with frequencies that are about equal in the corotating frame of the star. We discuss the implications of these results for the prospect of ? Scuti seismology.