Teegarden’s Miniature Star System: A Discovery Just Next Door to Our Own

When it comes to exploring distant worlds, proximity is key to making meaningful discoveries.

In a remarkable stroke of cosmic fortune, astronomers have revealed the potential discovery of not just one, but two Earth-like exoplanets orbiting an ancient star right at the edge of our galactic neighborhood.

Even more intriguing, these planets may be capable of supporting life.

Teegarden, the star at the center of the discovery, is just 12.5 light-years away—a mere cosmic hop. Despite its proximity, it’s so faint and small that it wasn't identified until 2003. Though it’s a red dwarf star, which is the most common type in the galaxy, it’s only about 10% of our sun’s mass. At 8 billion years old, this tiny red dwarf might be hiding more than meets the eye.

The exoplanet discovery was spearheaded by astronomers at the University of Göttingen, Germany, as part of the CARMENES project. This initiative is dedicated to identifying planets within the habitable zones of small red dwarf stars. A habitable zone is the ideal distance from a star where a planet can maintain liquid water—crucial for life. Due to Teegarden’s low temperature (only about 4,900°F or 2,700°C), its exoplanets must orbit extremely close to the star to be in this life-sustaining zone.

Even with their small star and tight orbits, 'the two planets resemble the inner planets of our own solar system,' remarked Mathias Zechmeister from the Institute for Astrophysics at the University of Göttingen in the press release. Zechmeister, the study’s lead author, also discussed the findings in the journal Astronomy & Astrophysics.

'These planets are just slightly heavier than Earth and reside in the so-called habitable zone, where liquid water could potentially exist,' Zechmeister explained in the press release.

The two exoplanets were detected by observing the wobble of the star as the planets' gravity gently tugged at it. These periodic shifts allowed astronomers to determine the planets' masses and orbital periods, further revealing their potential for hosting life.

Teegarden b, the closest of the two exoplanets, holds greater promise with a 60 percent chance of having a 'temperate surface environment' with temperatures between 32-122°F (0-50°C), according to the Planetary Habitability Laboratory. Teegarden b completes its orbit in just five days and is only 5 percent more massive than Earth. Its proximity to the star means it’s likely 'tidally locked,' with one side of the planet constantly facing the star, and the other in perpetual darkness. How life might adapt to such extreme conditions remains an open question.

Teegarden c, which orbits farther from the star with an orbital period of over 11 days, is likely to be colder, with surface temperatures resembling those of Mars. It’s about 10 percent more massive than Earth. However, as we only have data on the masses and orbital periods of these planets, more research is needed to assess their true habitability.

The discovery of two potentially habitable exoplanets is certainly thrilling, but other red dwarf star systems have proven to be treasure troves of exoplanets. Take TRAPPIST-1, for instance, which is home to seven exoplanets and lies nearly 40 light-years away. Could Teegarden also have more secrets to reveal? It’s possible. 'Many stars seem to be surrounded by multi-planet systems,' noted co-author Stefan Dreizler from Göttingen in the press release.

In other words, Teegarden might be harboring an entire planetary family. Being relatively close by, future telescopes could offer a closer look at these fascinating worlds, potentially uncovering whether they have atmospheres—and if those atmospheres might hold signs of life or habitability.