A Year Takes Only 21 Hours
TOI-3261 b orbits its star in just 21 Earth hours, it is a member of the super-rare class of ultra-short-period hot Neptunes, and it is subjected to a scorching temperature of some 1,500°C, rewiring traditional concepts of planetary physics
Discovery and Observational Methods
The planet was first detected using NASA’s Transiting Exoplanet Survey Satellite (TESS), which observed dips in the star’s brightness caused by planetary transits. The discovery was confirmed through observations from ground-based telescopes in Australia, Chile, and South Africa, which provided critical measurements of the planet’s properties.
Oddball Location in the “Hot Neptune Desert”
TOI-3261 b lives in the so-called hot Neptune desert, a region around stars where planets of this size and composition are few. Its current state is against expectations, as planets in such close orbits usually lose their gaseous envelopes due to strong stellar radiation and gravitational stripping.
Evolutionary History
Scientists believe TOI-3261 b started as a Jupiter-sized gas giant, forming further from its star. Over its 6.5 billion-year history,
two primary processes shaped its evolution:
Photoevaporation:
High-energy stellar emissions stripped lighter gases from its atmosphere.
Tidal Stripping:
Gravitational forces from the nearby star removed outer atmospheric layers
Its current density, twice that of Neptune, indicates that only heavier atmospheric elements remain, making it a valuable target for further study.
Implications for Planetary Science
The discovery of TOI-3261 b offers the first chance to test formation models and atmospheric dynamics at once. Scientists are eagerly awaiting the atmospheric composition using JWST, which will obtain infrared high-resolution observations to potentially show molecular “fingerprints.” The outcome will be better understood through physical processes governing hot giant planets throughout the universe.
Wider Perspective
TOI-3261 b joins an elite group of ultra-short-period hot Neptunes, including LTT-9779 b, TOI-849 b, and TOI-332 b, providing a comparative framework with which to study planetary evolution at extreme conditions. These kinds of discoveries could eventually lead to some breakthroughs in explaining why certain kinds of planets are so rare
Refer to the study published in The Astronomical Journal by Emma Nabbie et al.: “Surviving in the Hot-Neptune Desert: The Discovery of the Ultrahot Neptune TOI-3261b”.
