On the nature of the upper atmospheric variability in the rapidly oscillating Ap star HD134214

Recently, we discovered an entirely new type of variability in the upper atmospheres of rapidly oscillatingAp( roAp) stars. This manifests itself in amplitude modulation of the radial velocities that has not been previously detected in photometric studies of the same stars. To study this new variability further we obtained a full night, 8.85 h, of high time resolution ( 70 s), high spectral resolution ( R = 105 000), high signal- to- noise ratio ( on average S/ N similar to 130) data with Ultraviolet and Visual Echelle Spectrograph ( UVES) on the Very Large Telescope ( VLT) for the roAp star HD 134214. We also obtained 4.2 h of new photometric data in Johnson B with the South African Astronomical Observatory ( SAAO) 0.5- m telescope 2 d later. HD 134214 has been known for years to be singly periodic with a relatively stable amplitude in photometry; it has the highest pulsation frequency of any roAp star of 2.949 mHz ( P = 5.65 min). Our new UVES data show this principal frequency, plus five other frequencies in amplitude spectra of rare earth elements lines and the Ha line. The new frequencies are stable over the 8.85 h of observation, and the highest of them v2 = 2.782 mHz is the same as found in data taken 2 yr earlier with UVES presented in the discovery paper. The amplitudes of the new frequencies drop faster with atmospheric depth than does the amplitude of the principal frequency, hence explaining why they are generally not seen in broad- band photometric measurements that sample on average more deeply in the atmosphere. Our new photometric measurements also detect v2 for the first time in photometric data. Our analysis suggests that the new frequencies are associated with pulsation modes, but the nature of those modes and why they increase in amplitude with atmospheric height more strongly than the principal frequencies is not yet known.