Giant Planet Discovered Orbiting a Tiny Star Challenges Formation Theories

A groundbreaking discovery has left scientists puzzled as they found a massive gas giant orbiting a small red dwarf star. This rare combination challenges existing planetary formation theories. TOI-6894, located in our galaxy, is a red dwarf star with only about 20% of the Sun’s size, brightness, and mass. Traditionally, such stars were not considered capable of hosting giant planets. However, an international team of astronomers identified the unmistakable signature of a gas giant orbiting this minuscule star, according to a study published in Nature Astronomy. TOI-6894 holds the record for being the smallest star known to host such a colossal planet. The giant planet, named TOI-6894b, has a radius slightly larger than Saturn but only half its mass, completing one full orbit around its star every 3.36 days. Scientists used photometric data from NASA’s TESS satellite to detect it, later confirmed by ground-based telescopes like Chile’s Very Large Telescope (VLT). “Most stars in our galaxy are small like this, with low mass, and we didn’t believe until now that they could be accompanied by giant gas planets,” explained co-author Professor Daniel Bayliss from the University of Warwick. Researchers remain baffled about how such a low-mass star can form such a colossal planet. Current planetary formation theories suggest that the protoplanetary disk surrounding smaller stars lacks sufficient material for giants to form. An alternative theory involves gravitational instability where the disk fragments to form a planet directly. Yet, available data doesn’t fully support this either. Studying TOI-6894b’s atmosphere may shed light on its origins, revealing insights into its core structure and size. Interestingly, unlike most hot gas giants discovered so far, TOI-6894b is unusually ‘cold,’ with temperatures not exceeding 420 Kelvin (146.85°C). Methane likely dominates its atmosphere. Over the next 12 months, the James Webb Space Telescope will further investigate its atmosphere.