Stellar wobble caused by a nearby binary system: eccentric and inclined orbits

TL;DR

This paper models the stellar wobble caused by a nearby binary system with eccentric and inclined orbits, highlighting how such configurations can mimic planetary signals and discussing conditions for distinguishing them.

Contribution

It extends previous models to include eccentric and inclined binary orbits, analyzing their impact on stellar wobble and implications for exoplanet detection.

Findings

Eccentric and inclined binaries can mimic planetary signals, especially in coplanar, equator-on observations.

Eccentric binaries may produce larger wobble effects than circular ones.

High eccentricity in the binary's orbit can help distinguish binary effects from planetary signals.

Abstract

Most extrasolar planets currently known were discovered by means of an indirect method that measures the stellar wobble caused by the planet. We previously studied a triple system composed of a star and a nearby binary on circular coplanar orbits. We showed that although the effect of the binary on the star can be differentiated from the stellar wobble caused by a planet, because of observational limitations the two effects may often remain indistinguishable. Here, we develop a model that applies to eccentric and inclined orbits. We show that the binary's effect is more likely to be mistaken by planet(s) in the case of coplanar motion observed equator-on. Moreover, when the orbits are eccentric, the magnitude of the binary's effect may be larger than in the circular case. Additionally, an eccentric binary can mimic two planets with orbital periods in the ratio 2/1. However, when the star's orbit around the binary's center of mass has a high eccentricity and a reasonably well-constrained period, it should be easier to distinguish the binary's effect from a planet.