Transits of hot Jupiter TOI-2535 b observed to disappear over time

The hot Jupiter planet TOI-2535 b has provided a rare look at orbital evolution in action. Observations from the TESS satellite show that the planet's path across its star has shifted over seven years, eventually causing its transits to stop entirely. This phenomenon is driven by a hidden, massive planetary companion that pulls on the orbit of TOI-2535 b, causing it to precess out of our line of sight.

Star system: TOI-2535 | Distance from the Sun: 1114 light years

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Transits of hot Jupiter TOI-2535 b observed to disappear over time

Star system: TOI-2535 | Distance from the Sun: 1114 light years

The hot Jupiter TOI-2535 b is the first confirmed planet orbiting a single star that has been directly observed to cease its transit activity. A transit occurs when a planet passes directly in front of its parent star from our perspective on Earth, blocking a portion of the star's light. By monitoring this light over seven years using the Transiting Exoplanet Survey Satellite, the planet's path across the face of the star was shown to shift until it no longer crossed the stellar disk at all. This movement confirms that the orbital alignment of the planet is changing significantly on a human-observable timescale.

This shift in transit geometry was measured alongside transit timing variations, which are changes in the predicted time a transit should occur. Data from the NEID radial-velocity instrument, which measures the subtle gravitational tugs a planet exerts on its star, helped characterize the system's dynamics. The combined observations point to the presence of a second, unseen planet in the system. This massive, Saturn-sized companion is mutually inclined by at least five degrees relative to the first planet and interacts with it through gravitational forces. These interactions force the orbital planes of the planets to precess, or wobble, which causes the transit path of TOI-2535 b to move away from the star's center.

This system is unusual because it contains two giant planets in short-period orbits. The existence of these two planets, locked in a specific gravitational relationship known as mean-motion resonance, creates extreme orbital evolution. This discovery highlights how dynamic interactions between multiple planets can quickly change the orientation of their orbits, rendering transits temporary features that appear and disappear over relatively short periods of time.

Key findings
TOI-2535 b is the first planet observed to have its transits disappear due to orbital plane precession.
The planet's transit path shifted across the stellar disk at a rate of 0.16 per year.
Transit mid-times deviated by six hours from expected patterns.
A second, massive planetary companion of at least Saturn-mass is responsible for these orbital changes.
The two giant planets exist in a mean-motion resonance with a mutual orbital inclination of at least five degrees.

Scientific study

A TESS Disappearing Act: The Vanishing Transits of TOI-2535 b