Intriguing, Low-amplitude Periodicity in the Radial Velocities of \delta Sagittarrii

Session 102 - Pulsating Stars.
Display session, Thursday, January 18
North Banquet Hall, Convention Center

[102.13] Intriguing, Low-amplitude Periodicity in the Radial Velocities of \delta Sagittarrii

G. A. H. Walker, A. R. Walker (U. British Columbia), A. W. Irwin, A. M. Larson, S. L. S. Yang (U. Victoria)

We present the initial results of the analysis of the precise radial velocities of the relatively little-studied star \delta Sagittarii, K2.5 IIIa, HR 6859. The data were obtained at the Canada-France-Hawaii Telescope using the hydrogen fluoride absorption cell technique. The periodogram shows significant peaks at 2.8 days (K=104 m s^-1), 63 days (K=85 m s^-1), and 295 days (K=72 m s^-1). Because of our limited data the true period cannot be distinguished from these possibilities due to aliasing. This giant is an interesting example of a star having a radial velocity periodicity which may be attributed to intrinsic variability, rotational modulation, or the presence of a low M_2 \sin i companion (see A. Walker et al., this conference). More observations are urgently required to determine the true period and to discover the underlying origin for this star's radial velocity variability.

Program listing for Thursday