Discovery of a Giant Planet Orbiting a Tiny Star

An international team of astronomers, including researchers from the University of Liège and institutions in the UK, Chile, and the USA, has discovered a massive planet orbiting an exceptionally small star — the tiniest star ever found to host such a large companion.

Figure 1. Tiny Star, Monster Planet: Defying the Rules of Space.

The star, TOI-6894, is a red dwarf with just 20% of the Sun’s mass. Red dwarfs are the most common stars in the galaxy, yet it was long thought that stars this small lack the material necessary to form or sustain giant planets. Contrary to expectations, the team detected a Saturn-sized planet, named TOI-6894b, orbiting this star. The findings were published in Nature Astronomy. Figure 1 shows Tiny Star, Monster Planet: Defying the Rules of Space.

TESS First, Earth Confirms

NASA’s Transiting Exoplanet Survey Satellite (TESS) initially spotted the unusual signal as part of a broader search for giant planets around small stars, led by Dr. Edward Bryant of UCL’s Mullard Space Science Laboratory.

To confirm the discovery, follow-up observations were conducted using Earth-based telescopes, including those from the SPECULOOS and TRAPPIST projects coordinated by the University of Liège. Dr. Khalid Barkaoui, who led the follow-up, said:

A Record-Breaking Star-Planet System

TOI-6894 now holds the record as the smallest star ever discovered to host a transiting giant planet, with a radius 40% smaller than any previously known host. Prof. Jamila Chouquar, formerly at ULiège, remarked:

Rethinking Planet Formation

Current models suggest giant planets should be rare around small stars, as their protoplanetary disks — the gas and dust from which planets form — are believed to lack the material to build massive cores and thick gas envelopes. TOI-6894b challenges this assumption, opening new questions about how planets form around the galaxy’s most abundant stars.

A New Era of Exoplanet Discovery

“This giant planet orbiting a tiny star shows that planetary diversity in the galaxy is far greater than we imagined. Most of the stars we observe with SPECULOOS and TRAPPIST are similar — or even smaller — so we’re in an excellent position to uncover more cosmic outliers in the years ahead.”

This discovery not only challenges long-standing assumptions about planet formation but also opens the door to finding more unexpected giant planets around the galaxy’s smallest stars, ushering in a new era of exoplanet exploration.

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025), Tiny Star, Giant Rule-Breaking Planet: A Cosmic Oddity, AnaTechMaz, pp.495