Planetary system at V Hya?

Subject: Planetary system at V Hya? 25th February 2019, 4:39 am

Quote :: Recent Hubble Space Telescope observations found periodic, high-speed, collimated ejections (or "bullets") from the star V Hya (Sahai et al. 2016). The proposed model associated these bullets with the periastron passage of an unseen, substellar companion in an eccentric orbit and with an orbital period of ∼8 yrs. Here we propose that V Hya is part of a triple system, with a substellar companion having an orbital period of ∼8 yrs, and a tertiary object on a much wider orbit. In this model, the more distant object causes high-eccentricity excitations on the substellar companion's orbit via the Eccentric Kozai-Lidov mechanism. These eccentricities can reach such high values, leading to Roche-lobe crossing, producing the observed bullet ejections via a strongly enhanced accretion episode. For example, we find that a ballistic bullet ejection mechanism is consistent with a brown dwarf companion, while magnetically driven outflows are consistent with a Jovian companion. Finally, we suggest that the distant companion may reside at few hundreds AUs on an eccentric orbit.