Confirmed planetTeegarden's Star system
Teegarden's Star c
A roughly Earth-mass planet deeper in the habitable zone of a nearby red dwarf, slightly cooler than its inner sibling.
- Orbital period
- 11.41 days
- Distance from the star
- 0.0443 AU · 6.63 million km
- Minimum mass
- 1.11 Earth masses
- Radius
- Unknown; no transit detected
- Equilibrium temperature
- About 226 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
An Earth-mass world in the temperate zone
Teegarden's Star c completes an orbit every 11.41 days at about 0.044 AU from its star. Its minimum mass is near Earth's, and its equilibrium temperature of roughly 226 K places it comfortably inside the conservative habitable zone.
As with the system's inner planet, the mass is only a lower limit because the orbital inclination is unknown, and the radius is unmeasured. The planet was detected through the star's radial-velocity wobble rather than a transit.
A cooler sibling
Compared with Teegarden's Star b, planet c receives less energy and sits deeper in the habitable zone. If it has a suitable atmosphere, its surface could stay temperate; without one, it would be frozen. The difference between the two planets makes the pair a useful test of how small shifts in orbit change a planet's climate.
The host star's low activity and great age work in the planet's favour. An old, quiet red dwarf has had less violent youth in the recent past, though its early flare history could still have shaped any atmosphere long ago.
What we don't know
The true mass, size, composition, and atmosphere of Teegarden's Star c are all unknown. Future transit searches and direct-imaging attempts may fill in these gaps, and the planet's proximity makes it a leading candidate for atmospheric study.
- What is its true mass and radius?
- Does it hold an atmosphere and surface water?
- How do b and c differ in climate and composition?
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 about 11.4 Earth days.
It sits deeper in the habitable zone than its sibling b.
Only its minimum mass is known.