No magnetic field variation with pulsation phase in the roAp starγ Equulei

Abstract

We present an analysis of 210 high-resolution time-resolved spectropolarimetric observations of the roAp star γ Equ obtained over three nights in August and September 2003. Radial velocity variations due to p-mode non-radial pulsations are clearly detected in the lines of rare-earth elements, in particular Pr  ,N d and Nd . In contrast, we find absolutely no evidence for the variation of the mean longitudinal magnetic field over the pulsation period in γ Equ at the level of 110-240 G which was recently reported by Leone & Kurtz (2003). Our investigation of the variability of circularly polarized profiles of 13 Nd  lines demonstrates that, at the 3σ confidence level, no magnetic field variation with an amplitude above ≈40−60 G was present in γ Equ during our monitoring of this star.