TOI-1355 b: Giant planet orbits star in two days

A team of astronomers, including researchers from the University of Tokyo, has identified a rare exoplanet that challenges conventional models of planetary orbits. The planet, designated TOI‑1355 b, orbits its host star—TOI‑1355—in an unusually hot and eccentric trajectory, completing a full revolution in roughly two Earth days. The discovery was reported in the latest issue of the *Publications of the Astronomical Society of Japan*.

TOI‑1355 is itself a much hotter star than the Sun, and the planet’s rapid, elongated orbit places it far closer to its parent star than most known exoplanets. Such a combination of high stellar temperature and extreme orbital eccentricity is uncommon, making TOI‑1355 b a valuable laboratory for studying planetary migration and atmospheric dynamics under extreme conditions. The researchers employed transit photometry and radial‑velocity measurements to confirm the planet’s mass and orbital parameters, providing a robust dataset for future theoretical work.

The find expands the catalog of known “hot Jupiters” and highlights the diversity of planetary systems in our galaxy. By studying TOI‑1355 b’s unique characteristics, scientists hope to gain deeper insights into the processes that shape planetary orbits and the evolutionary pathways of close‑in gas giants.