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Centro de Astrofísica da Universidade do Porto

The discovery of 8.0-min radial velocity variations in the strongly magnetic cool Ap star HD154708, a new roAp star

D. W. Kurtz, V. G. Elkin, M. S. Cunha, G. Mathys, S. Hubrig, B. Wolff, I. Savanov

Abstract
HD154708 has an extraordinarily strong magnetic field of 24.5 kG. Using 2.5 h of high time resolution Ultraviolet and Visual Echelle Spectrograph (UVES) spectra we have discovered this star to be an roAp star with a pulsation period of 8 min. The radial velocity amplitudes in the rare earth element lines of Nd II, NdIII and Pr III are unusually low�∼60ms−1 � for an roAp star. Some evidence suggests that roAp stars with stronger magnetic fields have lower pulsation amplitudes. Given the central role that the magnetic field plays in the oblique pulsator model of the roAp stars, an extensive study of the relation of magnetic field strength to pulsation amplitude is desirable.

Keywords
stars: individual: HD154708 – stars: magnetic fields – stars: oscillations – stars:variables: other

Monthly Notices of the Royal Astronomical Society
Volume 372, Page 286
October 2006

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