Scientists Find Ultra‑Hot, Eccentric Exoplanet with Two‑Day Orbit
An international team of astronomers, including researchers from the University of Tokyo, has detected the exoplanet TOI-1355 b. The world orbits its host star TOI-1355 on a tight, markedly eccentric trajectory.
One full revolution takes only about two Earth days, indicating a rapid orbital speed that places the planet much closer to its star than Mercury is to the Sun.
The host star TOI-1355 is significantly hotter than our Sun, driving the planet’s surface temperature to extreme values. The mix of a short orbital period, a strongly eccentric orbit, and intense stellar irradiation makes TOI-1355 b a rare specimen in exoplanet science.
To pinpoint the planet, the scientists used measurements from the Transiting Exoplanet Survey Satellite (TESS), which recorded periodic dips in the star’s brightness. Analysis of these light curves yielded the short orbital period and the unusual shape of the orbit. Ground‑based telescopes complemented the data by refining the star’s properties.
The study appears in the journal Publications of the Astronomical Society of Japan. The authors anticipate that follow‑up observations will illuminate how such extreme planetary systems form and evolve.
The discovery underscores the diversity of planetary architectures. The combination of high stellar irradiation and an eccentric orbit may affect atmospheric evolution, a question slated for future investigation with instruments like the James Webb Space Telescope.