Asteroseismology of Massive Stars with the TESS Mission: The Runaway β Cep Pulsator PHL 346 = HN Aqr

We report an analysis of the first known β Cep pulsator observed by the Transiting Exoplanet Survey Satellite (TESS) mission, the runaway star PHL 346 = HN Aqr. The star, previously known as a singly periodic pulsator, has at least 34 oscillation modes excited, 12 of those in the g-mode domain and 22 p modes. Analysis of archival data implies that the amplitude and frequency of the dominant mode and the stellar radial velocity were variable over time. A binary nature would be inconsistent with the inferred ejection velocity from the Galactic disk of 420 km s−1 which is too large to be survivable by a runaway binary system. A kinematic analysis of the star results in an age constraint (23 ± 1 Myr) that can be imposed on asteroseismic modeling and that can be used to remove degeneracies in the modeling process. Our attempts to match the excitation of the observed frequency spectrum resulted in pulsation models that were too young

TESS lightcurves of gamma-Cas stars

gamma-Cas stars constitute a subgroup of Be stars showing unusually hard and bright X-ray emission. In search for additional peculiarities, we analyzed the TESS lightcurves of 15 gamma-Cas analogs. Their periodograms display broad frequency groups and/or narrow isolated peaks, often superimposed over red noise. The detected signals appear at low frequencies, with few cases of significant signals beyond 5/d (and all of them are faint). The signal amplitudes, and sometimes the frequency content, change with time, even in the absence of outburst events. On the basis of their optical photometric variability, gamma-Cas stars reveal no distinctive behaviour and thus appear similar to Be stars in general.Comment: accepted by MNRAS - the arxiv version has figures in low-resolutio

BRITE view of σ\sigma Scorpii, β\beta Cephei-type star studied for over a century

Preliminary results of the analysis of the combined space-based BRITE and SMEI, and ground-based Stroemgren photometry are presented. The BRITE data allowed to find seven p and three g modes in the frequency spectrum of this star; only four p modes were known in this star prior to this study. The first results of seismic modelling are also presented.Comment: 3 pages, 1 figure, to appear in the Proceedings of the 3rd BRITE Science Conference, Auberge du Lac Taureau, Canad