TOI-7510: A solar-analog system of three transiting giant planets near a Laplace resonance chain

Abstract

We report the confirmation and initial characterization of a compact and dynamically rich multiple giant planet system orbiting the solar analog TOI-7510. The system was recently identified as a candidate two-planet system in a machine-learning search of the TESS light curves. Using TESS data and photometric follow-up observations with ASTEP, CHEOPS, and EulerCam, we show that one transit was initially misattributed and that the system consists of three transiting giant planets with orbital periods of 11.5, 22.6, and 48.9 days. The planets have radii of 0.65, 0.96, and 0.94 R_J, making them the largest known trio of transiting planets. The system architecture lies near a 4:2:1 mean motion resonant chain, inducing large transit timing variations for all three planets. Photodynamical modeling gives mass estimates of 0.057, 0.41, and 0.60 M_J and favors low eccentricities and mutual inclinations. TOI-7510 is an interesting system for investigating the dynamical interactions and formation histories of compact systems of giant planets.

Figures (9)

• Figure 1: Known systems hosting three or more planets with masses (or minimum masses) between 14 $\mathrm{M_E}$ and 13 $\mathrm{M}_{\rm J}$, mass uncertainties below 20%, and orbital period uncertainties below 2%. Open circles indicate planets detected via radial velocity monitoring, while filled circles correspond to transiting planets. The circle sizes are proportional to the logarithm of the planetary mass. Period ratios between adjacent planets are annotated in black or in light gray if $P_{i+1}/P_i > 3.5$. Notably, the inner pair of TOI-7510 has a period ratio of 1.957, similar to the Uranus–Neptune ratio of 1.961. Lower-mass planets in these systems are excluded from the figure. Data were retrieved from the NASA Exoplanet Archive Akeson2013.
• Figure 2: Photodynamical modeling of the transit photometry. The dots, color coded by telescope, represent the noise-model-corrected observations. The black line shows the transit model. Vertical lines mark the midtransit time of planets b (blue), c (orange), and d (green) and are labeled by the number of orbital periods since the first observed transit.
• Figure 3: Posterior TTV predictions of planets b (blue band), c (orange band), and d (green band) computed relative to a linear ephemeris (Table \ref{['table:results']}). A thousand random draws from the posterior distribution were used to estimate the median TTV values and their uncertainties (68.3% confidence interval). The upper panel shows the posterior TTV values and compares them with the individual transit-time determinations (Table \ref{['table:transit_times']}, error bars). In the lower panel, the posterior median transit-timing value was subtracted to emphasize the uncertainty in the distribution and facilitate a clearer comparison with the individually determined transit times.
• Figure 4: Spectral energy distribution of TOI-7510. The solid line shows the MAP PHOENIX/BT-Settl interpolated synthetic spectrum, red circles are the absolute photometric observations, and gray open circles are the result of integrating the synthetic spectrum in the observed bandpasses. The lower panel shows the residuals of the MAP model, with the jitter added quadratically to the data error bars.
• Figure 5: Photodynamical modeling of the transit photometry. Each dataset is shown in a different panel, labeled with the midtransit date (or the start date of the observation for TESS) and the telescope (or instrument). The error bars, in different colors for each telescope (same color code as in Fig. \ref{['figure:phot']}), represent the observations. The black line is the MAP model that combines both transits and noise, while the gray line shows the pure transit model.