We were able to determine, for the first time, the surface structure and magnetic field geometry of a pulsating magnetic A star, the roAp HD 24712. RoAp stars exhibit high-overtone, low-degree, non-radialnp-mode pulsations with periods of 6 to 21 minutes and their observed pulsational amplitudes are modulated with the magnetic field variations, exhibiting maximum amplitude at the phases of highest magnetic field strength. This indicates a close connection between the magnetic field and the still unclear excitation mechanism of roAp pulsations. Read more...

68 stars in the field of NGC2264 were observed simultaneously with the MOST satellite, 34 of which were previously identified as potential targets to search for PMS pulsation. The routines SigSpec and Period04 were used for the frequency analysis. We discovered pulsation in 4 potential A and F type PMS members of NGC2264 with frequencies between 2.7 h and 23 min. For one of the PMS pulsators identified with MOST after the first days of observation, simultaneous ground-based Strömgren photometry was obtained with the OSN 0.9 m telescope and confirms the highest frequency identified in the MOST photometry. Read more...

Hybrid pulsators are stars that have at least two different types of oscillation excited, and thus are members of more than just one known class of pulsating stars. These objects may reveal more about their interior structure than ordinary pulsators, if a sufficient number of oscillation modes is excited and identified. The present work reports the first case of a star with enough modes detected: we found six high-order gravity modes and eight low-order radial and mixed modes for the bright equatorial Beta Cephei/SPB star Gamma Pegasi from high precision MOST photometry and accurate ground-based radial velocities. We provide mode identifications, preliminary asteroseismic modelling and discuss the implications of this finding. Read more...

A high percentage of the astrophysically important RR Lyrae stars show a periodic amplitude and/or phase modulation of their pulsation cycles. More than a century after its discovery, this "Blazhko effect" still lacks acceptable theoretical understanding. In one of the plausible models for explaining the phenomenon, the modulation is caused by the effects of a magnetic field. So far, the available observational data have not allowed us to either support nor rule out the presence of a magnetic field in RR Lyrae stars. Read more...