On the follow-up efforts of long-period transiting planet candidates detected with Gaia astrometry

Abstract

The class of transiting cold Jupiters, orbiting at $\gtrsim 0.5-1.0$ au, is to-date underpopulated. Probing their atmospheric composition and physical characteristics is particularly valuable, as it allows for direct comparisons with the Solar System giant planets. We investigate some aspects of the synergy between Gaia astrometry and other ground-based and space-borne programs for detection and characterization of such companions. We carry out numerical simulations of Gaia observations of systems with one cold transiting gas giant, using Jovian planets around a sample of nearby low-mass stars as proxies. Using state-of-the-art orbit fitting tools, we gauge the potential of Gaia astrometry to predict the time of transit centre $T_c$ for the purpose of follow-up observations to verify that the companions are indeed transiting. Typical uncertainties on $T_c$ will be on the order of a few months, reduced to several weeks for high astrometric signal-to-noise ratios and periods shorter than $\sim 3$ yr. We develop a framework for the combined analysis of Gaia astrometry and radial-velocity data from representative ground-based campaigns and show that combined orbital fits would allow to significantly reduce the transit windows to be searched for, down to about $\pm 2$ weeks ($2-\sigma$ level) in the most favourable cases. These results are achievable with a moderate investment of observing time ($\sim 0.5$ nights per candidate, $\sim 50$ nights for the top 100 candidates), reinforcing the notion that Gaia astrometric detections of potentially transiting cold giant planets, starting with Data Release 4, will constitute a valuable sample worthy of synergistic follow-up efforts with a variety of techniques.

9 pages, 6 figures. Accepted for publication in MNRAS

References in corpus (31)

• The Gaia mission
• Gaia Early Data Release 3: The astrometric solution
• EXOFAST: A fast exoplanetary fitting suite in IDL
• Astrometric exoplanet detection with Gaia
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G=18.5
• Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data
• Double-blind test program for astrometric planet detection with Gaia
• The population of long-period transiting exoplanets
• Gaia's potential for the discovery of circumbinary planets
• The PLATO field selection process I. Identification and content of the long-pointing fields
• Parameters and Predictions for the Long-Period Transiting Planet HD 17156b
• Predicting the Exoplanet Yield of the TESS Prime and Extended Missions Through Years 1-7
• Revisiting the Long-Period Transiting Planets from Kepler
• The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 day Orbit with the Automated Planet Finder Telescope
• Limits of ultra-high-precision optical astrometry: Stellar surface structures
• Two long-period transiting exoplanets on eccentric orbits: NGTS-20 b (TOI-5152 b) and TOI-5153 b
• A transit timing variation observed for the long-period extremely low density exoplanet HIP 41378f
• A long period (P = 61.8-d) M5V dwarf eclipsing a Sun-like star from TESS and NGTS
• Predictions of Astrometric Jitter for Sun-like Stars. II. Dependence on Inclination, Metallicity, and Active-Region Nesting
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. I. Confirmation of an Eccentric, Cool Jupiter With an Interior Earth-sized Planet Orbiting Kepler-1514
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit
• Activity time series of old stars from late F to early K. V. Effect on exoplanet detectability with high-precision astrometry
• An examination of the effect of the TESS extended mission on southern hemisphere monotransits
• Utilizing a global network of telescopes to update the ephemeris for the highly eccentric planet HD 80606 b and to ensure the efficient scheduling of JWST
• Multiple Explanations for the Single Transit of KIC 5951458 based on Radial Velocity Measurements Extracted with a Novel Matched-template Technique
• A new estimation of astrometric exoplanet detection limits in the habitable zone around nearby stars
• A celestial matryoshka: Dynamical and spectroscopic analysis of the Albireo system
• CHEOPS observations of TESS primary mission monotransits
• Constraining Orbital Periods from Nonconsecutive Observations: Period Estimates for Long-Period Planets in Six Systems Observed by K2 During Multiple Campaigns
• Following up TESS Single Transits With Archival Photometry and Radial Velocities
• Transit-period search from single-event space-based data: the role of wide-field surveys

Cited by in corpus (4)

• The PLATO field selection process. II. Characterization of LOPS2, the first long-pointing field
• Prospects from TESS and Gaia to constrain the flatness of planetary systems
• Dark Exoplanets
• The SPHERE infrared survey for exoplanets (SHINE). V. Complete observations, data reduction and analysis, detection performances, and final results