Detectability of Exoplanets in the Beta Pic Moving Group with the Gemini Planet Imager

TL;DR

This study models the potential for the Gemini Planet Imager to detect exoplanets around young, nearby stars in the Beta Pic Moving Group, considering various formation and orbital distribution scenarios.

Contribution

It introduces a comprehensive modeling procedure to predict exoplanet detectability with GPI around BPMG stars, accounting for different formation mechanisms and orbital distributions.

Findings

GPI can detect exoplanets around F and G stars in BPMG with probabilities depending on models.

Detection around K to M1 stars is limited by distance and brightness, especially beyond 10 pc.

Only one of four A stars in the sample is suitable for GPI detection due to brightness constraints.

Abstract

We model the detectability of exoplanets around stars in the Beta Pic Moving Group (BPMG) using the Gemini Planet Imager (GPI), a coronagraphic instrument designed to detect companions by imaging. Members of the BPMG are considered promising targets for exoplanet searches because of their youth (~12 MY) and proximity (median distance ~35 pc). We wrote a modeling procedure to generate hypothetical companions of given mass, age, eccentricity, and semi-major axis, and place them around BPMG members that fall within the V-band range of the GPI. We count as possible detections companions lying within the GPI's field of view and H-band fluxes that have a host-companion flux ratio placing them within its sensitivity. The fraction of companions that could be detected depends on their brightness at 12 Myr, and hence formation mechanism, and on their distribution of semi-major axes. We used brightness models for formation by disk instability and core-accretion. We considered the two extreme cases of the semi-major axis distribution - the log-normal distribution of the nearby F and G type stars and a power-law distribution indicated by the exoplanets detected by the radial velocity technique. We find that the GPI could detect exoplanets of all the F and G spectral type stars in the BPMG sample with a probability that depends on the brightness model and semi-major axis distribution. At spectral type K to M1, exoplanet detectability depends on brightness and hence distance of the host star. GPI will be able to detect the companions of M stars later than M1 only if they are closer than 10 pc. Of the four A stars in BPMG sample, only one has V-band brightness in the range of GPI; the others are too bright.