TOI-1355 b: Eccentric Hot Jupiter Orbiting an Extremely Hot Star

Astronomers from the University of Tokyo and international collaborators discovered an unusual exoplanet named TOI-1355 b orbiting a hot star with a surface temperature of approximately 8,400 degrees Celsius or 15,152 degrees Fahrenheit. Published on September 18, 2026, in the Publications of the Astronomical Society of Japan, the study reveals that this giant gas planet completes an orbit every two Earth days while following a highly elliptical path instead of a circular one. The researchers explain that the planet's eccentric trajectory likely originated from past gravitational interactions with other massive celestial bodies before experiencing tidal effects from its host star. This discovery provides critical insights into the orbital migration and evolutionary history of hot Jupiters surrounding unusually hot stars. The analysis relies on data from NASA's Transiting Exoplanet Survey Satellite, which detected brightness drops during transits and secondary eclipses. The anomalous timing of the secondary eclipse first alerted the research team, led by Project Researcher Noriharu Watanabe and Professor Norio Narita, to the planet's elongated orbit. Scientists emphasize that observation opportunities will become severely limited after around 2033 due to the planet's evolving orbital geometry, which will prevent transit viewings from Earth for hundreds of years. The team plans future observations using NASA's James Webb Space Telescope to further investigate the orbital tilt and atmospheric characteristics.