Researchers identify rare exoplanet providing insights into planetary formation

A research team led by Chalmers University of Technology has analyzed the characteristics of exoplanet TOI-733b, as detailed in the journal Astronomy & Astrophysics. Located 245 light-years away, the planet is nearly twice the size of Earth and orbits its host star every 4.9 days.

Using data from NASA’s TESS satellite, astronomer Iskra Georgieva and her colleagues determined that the planet has likely shed its original hydrogen and helium atmosphere. This observation is significant as it provides evidence regarding the boundary between rocky planets and larger gaseous planets, a concept often referred to in the study of the "radius valley."

Scientists hypothesize that the atmosphere may have been stripped away either by intense stellar radiation, a process known as photo-evaporation, or by geothermal heat emanating from the planet's core. Given its proximity to its star, TOI-733b appears to represent a critical size threshold where planetary atmospheres are frequently lost during the early stages of a star system's development.

The findings contribute to broader questions regarding how planets evolve and how often similar atmospheres are lost. Future research aims to clarify which physical mechanisms dominate during these early evolutionary stages.