TOI-1855 b: A Jupiter-like World in a Close Orbit

TOI-1855 is a star 577 light-years away with one known planet. The star is 8.2 billion years old and has a mass of 0.987 solar masses, a radius of 1.04 solar radii, and a temperature of 5360 K. Its radius is larger than the Sun's, while its temperature is cooler.

The planet, TOI-1855 b, was discovered by transit in 2024. A transit occurs when a planet passes in front of its star from our viewpoint, causing a small dip in observed brightness. TOI-1855 b is classified as Jupiter-like, a size class for planets exceeding 4 times Earth's radius. Its radius is 18.5 Earth radii, larger than Earth's, and its mass is 360 Earth masses, also larger than Earth's. This mass is roughly 1.13 times Jupiter's mass. Its orbital period is 1.36 days, and its mean density is 0.314 g/cm³, 0.0569 times Earth's.