%0 Journal Article
%T Radial velocities of pulsating subdwarf B stars: KPD 2109+4401 and PB 8783
%A Simon Jeffery
%A Don Pollacco
%J Physics
%D 2000
%I arXiv
%R 10.1046/j.1365-8711.2000.03634.x
%X High-speed spectroscopy of two pulsating subdwarf B stars, KPD 2109+4401 and PB 8783, is presented. Radial motions are detected with the same frequencies as reported from photometric observations and with amplitudes of ~2 km/sec in two or more independent modes. These represent the first direct observations of surface motion due to multimode non-radial oscillations in subdwarf B stars. In the case of the sdB+F binary PB 8783, the velocities of both components are resolved; high-frequency oscillations are found only in the sdB star and not the F star. There also appears to be evidence for mutual motion of the binary components. If confirmed, it implies that the F-type companion is >~1.2 times more massive than the sdB star, while the amplitude of the F star acceleration over 4 hours would constrain the orbital period to lie between 0.5 and 3.2d.
%U http://arxiv.org/abs/astro-ph/0005041v1