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arXiv · 1902.08206

Unseen companions of V Hya inferred from periodic ejections

Jesus M. Salas·Smadar Naoz·Mark R. Morris·Alexander P. Stephan
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Abstract

A recent study using $Hubble$ $Space$ $Telescope$ observations found periodic, high-speed, collimated ejections (or "bullets") from the star V Hya. The authors of that study proposed a model associating these bullets with the periastron passage of an unseen, substellar companion in an eccentric orbit and with an orbital period of $\sim8$ yrs. Here we propose that V Hya is part of a triple system, with a substellar companion having an orbital period of $\sim8$ 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 that they lead 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 can be produced by a brown-dwarf-mass companion, while magnetically driven outflows are consistent with a Jovian-mass companion. Finally, we suggest that the distant companion may reside at few a hundred AU on an eccentric orbit.

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Jesus M. Salas, Smadar Naoz, Mark R. Morris, Alexander P. Stephan. 2019-02-21. Unseen companions of V Hya inferred from periodic ejections. https://doi.org/10.1093/mnras/stz1515

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