Observational Techniques for Detecting Planets in Binary Systems

Abstract

Searches for planets in close binary systems explore the degree to which stellar multiplicity inhibits or promotes planet formation. There is a degeneracy between planet formation models when only systems with single stars are studied – several mechanisms appear to be able to produce such a final result. This degeneracy is lifted by searching for planets in binary systems; the resulting detections (or evidence of non-existence) of planets in binaries isolates which models may contribute to how planets form in nature. Some models in which giant planet formation occurs over large amounts of time (e.g., the core-accretion scenario) predict that an extra-turbulent environment, such as those around binary stars, will disrupt planet formation. If the timescale is short (as in the gravitational instability theory), the process may continue, or even be enhanced due to additional instabilities in the planet-forming disks. It may be that multiple mechanisms contribute to giant planet formation in nature. Establishing the rate at which giant planets exist in binaries will distinguish the relative frequencies at which different processes contribute.