Speaker
Description
One of the leading theories regarding the origin of the long secondary period (LSP) phenomenon in luminous red giants is binarity. In such a scenario, the red giant resides in a close binary system with a substellar object or a very low-mass star. In turn, the radial velocity curves of LSP stars suggest that a potential companion has an eccentric orbit. This may lead to the driving of so-called tidally excited oscillations (TEOs) in the red giant, which are observed in about 10% of close eccentric binary systems, including those containing evolved stars. TEOs are excited when the periodically varying tidal potential induced by the companion drives pulsations with frequencies coinciding with integer multiples of the orbital frequency. Since the explanation of the LSP phenomenon still remains inconclusive, we decided to search for possible TEO modes in relatively bright LSP stars and identified promising candidate(s). The presence of TEO modes in LSP variables may serve as another independent piece of evidence supporting the binarity hypothesis for these variables.