StarTeegarden's Star system
Teegarden's Star
One of the nearest stars to the Sun: a faint, extremely quiet red dwarf 12.5 light-years away, circled by two temperate, roughly Earth-mass planets and an outer candidate.
- Star type
- M7.0V red dwarf
- Distance
- 12.49 light-years · 3.83 parsecs
- Mass
- 0.089 solar masses
- Mean radius
- 0.107 solar radii
- Luminosity
- About 0.0007 solar luminosities
- Surface temperature
- About 2,900 K
- Rotation
- About 100 days
- Age
- About 8 billion years
A quiet neighbor, found late
Teegarden's Star is one of the closest stars to the Sun, yet it was not recognised until 2003. Astronomers found it by mining old photographic sky surveys for stars with unusually large apparent motion across the sky, the signature of a nearby object. It lies in the constellation Aries.
Despite being only 12.5 light-years away, it is far too faint to see without a telescope. Its dimness and slow crawl across the sky kept it hidden in plain sight for decades, and it remains among the least luminous stars in our immediate neighbourhood.
Red and remarkably still
Teegarden's Star is a low-mass M dwarf with about 9% of the Sun's mass and a surface temperature near 2,900 K. Most light it emits is in the infrared. It rotates very slowly, roughly once every 100 days, and is unusually inactive for an M dwarf, with little flaring or surface magnetic noise.
That calm is valuable. Magnetic activity on the star can mimic or hide the tiny wobbles caused by planets, so a quiet star makes those planet signals easier to trust.
Two temperate Earth-mass worlds
In 2019, the CARMENES radial-velocity survey reported two planets, Teegarden's Star b and c, each with a minimum mass close to Earth's. Both orbit inside the star's habitable zone, making this one of the nearest systems with temperate, roughly Earth-mass planets. A 2024 analysis added an outer candidate, Teegarden's Star d.
The planets do not transit, so their radii and true masses are unknown. Their minimum masses come from the star's back-and-forth motion along our line of sight, and the true values would be larger if the orbits are tilted.
How we study it
The system is a prime target for precise radial-velocity work in both visible and near-infrared light, where red dwarfs emit most of their energy. Future telescopes may attempt to detect the planets' heat directly or search for transits that would reveal their sizes. Because the star is so close and quiet, it is also a test case for detecting faint atmospheric or biosignature signals.
Key publications
| Year | Paper | Venue | Link |
|---|---|---|---|
| 2019 | Zechmeister et al., The CARMENES search for exoplanets around M dwarfs: two temperate Earth-mass planet candidates around Teegarden's Star | A&A 627, A49 | DOI |
| 2024 | Dreizler et al., updated radial-velocity analysis reporting Teegarden's Star d | A&A 684, A117 | ADS |
Values compiled from the NASA Exoplanet Archive and the papers listed above.
Worth knowing
It is among the nearest star systems to the Sun.
It was discovered in 2003, long after many more distant stars.
It rotates about once every 100 days and flares very little.