Testing the planetary hypothesis of NY Virginis: anticipated change in the eclipse timing trend within the next five years

Abstract

ABSTRACT Regarding the recent debate about the potential circumbinary exoplanets around NY Virginis (NY Vir), we analysed mid-eclipse timings of NY Vir using archival photometric data as well as our own observations and the ones from TESS. For this purpose, we first modelled the available eclipse light curves of the binary system to determine the masses of the stars. Then, we measured mid-eclipse times by fitting the light-curve model cycle-to-cycle to the light curves from TESS and our observations. By fitting a Newtonian eclipse timing model to the data, which takes both the light-time effect and potential mutual gravitational interactions into account, we derived orbital parameters and masses of the potential circumbinary planets assuming both eccentric and circular orbits. The models without a quadratic term that can model any possible secular trend, converged to comparable results. Dynamical stability tests show that our Newtonian timing solution corresponds to stable orbital configurations for two circumbinary planets with masses ∼2.3 and ∼4.0 MJup in orbits with very low eccentricity. Our analyses show that the addition of quadratic term for modelling the eclipse timing variation may induce the planetary orbits to be eccentric, hence more likely to be unstable. According to our findings, an upward trend in the eclipse timings followed by a downward one within the next five years is expected due to binary motion induced by circumbinary planets.