The new collection of TESS massive heartbeat stars with TEOs

The pie chart below shows the predicted percentage “composition” of the current sample of massive main-sequence stars. the “heartbeat” Our research is kindly supported byOur study is based on the data delivered by The new collection of TESS massive heartbeat stars with TEOs Piotr A. Kołaczek-Szymański *, Yaël Nazé , and Grégor Rauw 1,2, 1 1 A „digestible” poster STAR Institute, Université de Liège, Quartier Agora, Allée du 6 Août 19c, Bât. B5c, 4000, Liège, Belgium 1 Instytut Astronomiczny, Wydział Fizyki i Astronomii, Uniwersytet Wrocławski, Kopernika 11, 51-622 Wrocław, Poland 2 ... just follow the steps below to grasp its content Acknowledgements. PKS was supported by the University of Liège under the Special Funds for Research, IPD-STEMA Programme. YN and GR appreciate the financial support from FNRS and the University of Liège. *e-mail: [email protected] (right column) Example of a massive HBS from our sample with a pair of low-n TEOs, where “n” denotes the number of the harmonic of the orbital frequency. The analysis of HBSs with such TEOs is the most challenging, because it is difficult to separate the “heartbeat” from the TEOs themselves. If you are interested in details, stay tuned for our forthcoming paper: Kołaczek-Szymański, Nazé, and Rauw, A&A, (on the edge of submission) Worth remembering... We have found about 40 massive HBSs whose photometric variability has not been analyzed so far. Some of them were not recognized as binary systems until now. In about a dozen of these systems, we detected several TEOs per object that occur together with self-excited oscillations. Our main objectives... ...and the strategy applied TEOs (i.e., dynamical tides) are the dominant form of tidal dissipation in massive binary systems, shaping the evolution of their orbits. The efficiency of these processes is still uncertain. To help constrain properties of TEOs, we searched for new massive HBS systems and investigated whether TEOs occur in them and if their amplitudes change over time. We selected candidate stars earlier than spectral type B3, lacking any SPOC light curves. We extracted those from TESS FFIs and analyzed them with Fourier methods. Proximity effects were modeled using the eBEER formulae (Engel et al. 2020). The figure on the right shows the TESS light curve of the example massive HBS, MACHO 80.7443.1718, with the “heartbeat” and several TEOs being highlighted. TEOs TEOs Heartbeat stars (HBSs) are a group of eccentric binary systems in which combined proximity effects, such as ellipsoidal distortion and irradiation effect, give rise to a periodic light curve with a characteristic “pulse” every periastron passage, which can resemble an electrocardiogram signal. Tidally excited oscillations (TEOs) are normal modes forced by the varying tidal potential of a companion, which periodically approaches and recedes from the star. (effectively) single 22% products of binary interaction 28% pre-mass transfer binaries 50% after de Mink et al. (2014), ApJ, 782 Therefore, observations of the massive HBSs are a chance to study these systems at the moment when their tides are progressing toward stronger forms of interaction, e.g., leading to mass transfer or mergers. Gallery with some interesting cases we found (left column) Comparison of the light curves of the same massive HBS in TESS sectors 37 (top) and 64 (bottom). Indeed, it is still the same object, although it is hard to believe! All TEOs in this system exhibit significant changes in their amplitudes within timescale of just one year. © allWISE (NIR/MIR) © DSS2 (VIS) (middle column) Phased light curve of a massive HBS with high eccentricity and several TEOs superimposed (top). The system is surrounded by a nebula, pronounced both in the infrared (middle) and in visible light (bottom). A bow-like structure can also be seen in the infrared. The presence of this nebula may suggest that the system is very young and the secondary component is still in the PMS phase, or that the system has experienced enhanced mass loss in the past due to binary interactions. We discovered that the amplitudes of some TEOs change significantly on a timescale of just a year, which so far has been observed only for MACHO 80.7443.1718.