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Hot Jupiter TOI-2535b stops transiting its star; unseen companion suspected

2d

Summary

  • The hot Jupiter exoplanet TOI-2535b orbits its host star TOI-2535, a K dwarf smaller than the Sun, once every eight days.
  • After about seven years of observed transits, TOI-2535b stopped transiting its star in the most recent observations.
  • Transit timings shifted by up to six hours and transit durations grew progressively shorter before the transits ceased.
  • Researchers suspect an unseen companion, at least Saturn-sized and orbiting in a different plane, is changing the planet's orbital inclination.
  • Modeling found the system is stable mainly when the two planets sit in an orbital resonance; the study was published in The Astrophysical Journal Letters in 2026.

Reactions

  • The researchers wrote in the paper that this is the fastest rate of inclination change observed for an exoplanet orbiting a single star.
  • Commentary noted that a Jupiter-sized planet like TOI-2535b should not be that easy to shift out of transiting its star.
  • Commentary judged that how the TOI-2535 system reached its current state probably cannot be answered with further observations.
  • Commentary argued that without an additional event mixing up the orbits, it is not obvious how the system came to be in its current state.

Timeline newest first

  1. Researchers reported that TOI-2535b, a hot Jupiter orbiting the K dwarf star TOI-2535 every eight days, stopped transiting its star after about seven years of observed transits.
  2. The timing of TOI-2535b's transits shifted by as much as six hours, and transit durations grew progressively shorter in later observations, suggesting transits moved from the star's equator toward one of its poles.
  3. Researchers suspect an unseen second planet orbiting TOI-2535 in a different plane caused the transits to stop; it does not appear in Transiting Exoplanet Survey Satellite data.
  4. Researchers modeled 300,000 starting configurations of the TOI-2535 system, then ran the 100 best forward for a million years; about two-thirds became unstable.
  5. The stable solutions require the second planet around TOI-2535 to be at least roughly Saturn-sized and the angle between the two orbits not too large.
  6. As of the study, there was not enough clean radial velocity data to detect the second planet around TOI-2535, and transit timing noise means a third planet cannot be excluded.
  7. The report on TOI-2535b was published in The Astrophysical Journal Letters in 2026.

Sources newest first

  • The amazing disappearing exoplanetarstechnica.com· 2d

    John Timmer's Ars Technica article reports that TOI-2535b, a hot Jupiter watched transiting its K dwarf star for about seven years, stopped transiting, with its transit times shifting by up to six hours and durations shortening. The researchers suspect an unseen companion, at least Saturn-sized and orbiting in a different plane, is causing what they call the fastest rate of inclination change observed for an exoplanet around a single star.