WASP-63b

Lore & Background

WASP-63b was discovered in 2012 via the transit method as part of the Wide Angle Search for Planets. It orbits its host star on a tight, circular orbit, which has caused the planet to become highly inflated—its radius is much larger than expected for its mass, which is similar to Saturn. The planet's atmosphere has been found to contain water, and observations suggest the presence of a high cloud deck, though the composition of those clouds remains indeterminate.

The system received its names in June 2023 through the NameExoWorlds campaign, with the planet named Regoč after a character from Croatian Tales of Long Ago by Ivana Brlić-Mažuranić. The star itself is named Kosjenka after another character from the same work. The planet's equilibrium temperature and measured dayside temperature have been recorded but are not specified in available summaries.

Reader's Guide

WASP-63b (Regoč) is significant as an example of a highly inflated hot Jupiter–like planet, demonstrating how close-in gas giants can swell to sizes far exceeding their mass would suggest. Its discovery in 2012 added to the growing census of transiting exoplanets that allow atmospheric characterization. The detection of water in its atmosphere and the inference of a high cloud deck contribute to understanding the diversity of exoplanet atmospheres, particularly for planets orbiting evolved stars. The system's naming in 2023 as part of the NameExoWorlds campaign, with names drawn from Croatian folklore, highlights the cultural dimension of exoplanet discovery and public engagement. The planet's host star, Kosjenka, is an old, slightly metal-rich G-type subgiant, and the planet's inflated state may be linked to the star's evolved status and increased irradiation over time.

Did You Know?

• WASP-63b has a mass similar to Saturn but is highly inflated due to its proximity to its star.
• The planet's atmosphere contains water and likely has a high cloud deck of indeterminate composition.