Teegarden's Star d
Teegarden's Star d is a terrestrial planet orbiting Teegarden's Star in the constellation Aries. It lies about 13 light-years from Earth and was discovered in 2024 using the radial velocity method.
Is Teegarden's Star d in the Habitable Zone?
Teegarden's Star d orbits beyond the outer edge of the habitable zone of Teegarden's Star. At that distance, any surface water would almost certainly be frozen.
Habitable zone of Teegarden's Star: 0.022–0.059 AU (conservative: 0.028–0.056 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Teegarden's Star d
The equilibrium temperature of Teegarden's Star d is about 159 K (-114 °C) — well below freezing. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 0.12 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Teegarden's Star d — one full orbit around Teegarden's Star — lasts 26.1 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.079 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.07).
How Was Teegarden's Star d Discovered?
Teegarden's Star d was discovered in 2024 using the radial velocity method, with observations from Multiple Observatories.
The radial velocity method measures the subtle wobble of a star caused by the gravitational pull of an orbiting planet, visible as periodic shifts in the star's light spectrum. The size of the wobble reveals the planet's minimum mass.
How Far Away Is Teegarden's Star d?
Teegarden's Star d is 12.5 light-years (3.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 2014. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 220,000 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. Teegarden's Star d scores 0.44, ranking #360 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Teegarden's Star
Teegarden's Star
- Surface temperature
- 3,034 K (Sun: 5,772 K)
- Mass
- 0.10 M☉
- Radius
- 0.12 R☉
- Luminosity
- 0.0007 L☉
The Teegarden's Star Planetary System
Teegarden's Star d is one of 3 known planets in the Teegarden's Star system. Its siblings:
- Teegarden's Star b (Terrestrial)
- Teegarden's Star c (Terrestrial)
Teegarden's Star d — Complete Data
| Mass (best estimate) | 0.82 Earth masses |
|---|---|
| Orbital period | 26.13 days |
| Orbital distance | 0.079 AU |
| Eccentricity | 0.070 |
| Equilibrium temperature | 159 K (-114 °C) |
| Stellar irradiation | 0.12× Earth |
| Earth Similarity Index | 0.44 |
| Distance from Earth | 12.5 light-years (3.8 parsecs) |
| Constellation | Aries |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2024 |
Data: NASA Exoplanet Archive, last updated 2024-03-05. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Teegarden's Star d
Is Teegarden's Star d habitable?
No — Teegarden's Star d orbits outside the habitable zone of Teegarden's Star and is likely too cold for liquid water on its surface.
How far away is Teegarden's Star d?
Teegarden's Star d is about 13 light-years from Earth in the constellation Aries. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 220,000 years to get there.
How long is a year on Teegarden's Star d?
One orbit around Teegarden's Star takes 26.1 Earth days — short enough that 14 of its years would fit into one Earth year.
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