HD 4308 b — 4.1 times Earth's width (estimated from its mass, not measured), Neptune-sized; its year lasts 16 days; about 530 °C, hotter than boiling water; found in 2005 by radial velocity.
NASA Exoplanet Archive, Planetary Systems Composite Parameters (fetched 2026-11-02). Composite values: where a planet's size or mass was not measured, the archive estimates it from the other.
This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.