Confirmed planetTeegarden's Star system
Teegarden's Star b
A roughly Earth-mass planet in the inner part of the habitable zone of one of the nearest, quietest red dwarfs known.
- Orbital period
- 4.91 days
- Distance from the star
- 0.0252 AU · 3.77 million km
- Minimum mass
- 1.05 Earth masses
- Radius
- Unknown; no transit detected
- Equilibrium temperature
- About 301 K without an atmosphere
- Rotation
- Unknown
- Discovery
- 2019 · radial velocity
- Host star
- M7.0V red dwarf · about 0.09 solar masses
- Distance from the Sun
- 12.5 light-years
A temperate Earth-mass world next door
Teegarden's Star b was found in 2019 by the CARMENES survey, which watches nearby M dwarfs for the tiny wobbles produced by planets. The planet circles its star every 4.91 days, yet because the star is so faint, its equilibrium temperature is near Earth's own mean.
The measurement is a minimum mass of about 1.05 Earth masses. Since the orbit's tilt is unknown, the true mass could be higher. No transit has been seen, so the planet's radius and density are not measured.
Inside the habitable zone
With an equilibrium temperature around 301 K, Teegarden's Star b sits in the inner, optimistic part of the habitable zone. Whether its surface could actually hold liquid water depends on an atmosphere that has not been detected, and on whether any water survived the star's history.
Teegarden's Star is unusually quiet for an M dwarf, which is encouraging: less flaring means less radiation stripping away an atmosphere. But quietness only raises the possibility; it does not establish habitability.
What we don't know
The planet's true mass, size, composition, and atmosphere are all unknown. Future observations may detect a transit to measure its radius, or directly image its heat. Its closeness to the Sun makes it a high-priority target for such studies.
- What is its true mass and size?
- Does it have an atmosphere and surface water?
- Is its rotation synchronised with its orbit?
Key publications
| Year | Paper | Venue | Link |
|---|---|---|---|
| 2019 | Zechmeister et al., Two temperate Earth-mass planet candidates around Teegarden's Star | A&A 627, A49 | DOI |
| 2024 | Dreizler et al., updated radial-velocity analysis of the Teegarden's Star system | A&A 684, A117 | ADS |
Values compiled from the NASA Exoplanet Archive and the papers listed above. Minimum masses assume an unknown orbital inclination.
Worth knowing
Its year lasts just under 5 Earth days.
It orbits one of the nearest stars to the Sun.
Only its minimum mass is known.