HD 25295 b confirmed as a hot sub-Neptune and prime target for future atmospheric studies

HD 25295 b, also known as TOI-4602 b, is a sub-Neptune planet orbiting a bright and quiet star. Precise measurements of its mass and radius show that it is about 2.5 times the size of Earth and 5.5 times as massive. This places it just above the so-called radius valley, a region where few planets are found, and suggests that it is in transition between a sub-Neptune and a super-Earth.

The planet's bulk density indicates that it still has a thin atmosphere, but it may be slowly losing it and evolving toward a bare rocky core. The host star's brightness and stability make HD 25295 b an excellent candidate for future atmospheric studies with telescopes like JWST and the upcoming Ariel mission. Simulations show that these observatories will be able to measure the planet's atmospheric composition, helping scientists understand how planets lose their atmospheres and move from sub-Neptunes to super-Earths.

These findings make HD 25295 b a key object for studying the physical processes that shape the diversity of small exoplanets.

Key findings
- HD 25295 b is a confirmed sub-Neptune with a mass of 5.5 Earth masses and a radius of 2.5 Earth radii
- The planet is just above the radius valley, suggesting it is losing its atmosphere
- Its bright, quiet host star makes it ideal for atmospheric characterization
- JWST and Ariel will be able to study its atmosphere in detail
- The planet offers insights into the transition from sub-Neptunes to super-Earths

Scientific study

The GAPS Programme at TNG. LXXIII. Confirmation of the hot sub-Neptune TOI-4602 b (HD 25295 b), a key target for future atmospheric characterization (external link)