Editing Teegarden's Star (section)

== Planetary system ==

Observations by the ROPS survey in 2010, published in 2012, showed variation in the [[radial velocity]] of Teegarden's Star, though there was insufficient data to make claims of planet detection at that time.<ref name=ROPS1/> <!-- The source uses the 'name' "SO J025300.5+165258" -->

In June 2019, scientists conducting the CARMENES survey at the [[Calar Alto Observatory]] announced evidence of two [[Earth analog|Earth-mass exoplanets]] orbiting the star within its [[Circumstellar habitable zone|habitable zone]];<ref name="CARMENES"/><ref name="EA-20190618"/> [[Teegarden's Star b]] orbits inside the optimistic habitable zone—the equivalent in the Solar System would be in between Earth and Venus—whereas [[Teegarden's Star c]] orbits on the outer edge of the conservative habitable zone, similarly to Mars.<ref name="CARMENES" />

A 2024 study detected a third planet orbiting farther out, with a period of 26 days and a [[minimum mass]] slightly less than Earth's mass. This third planet, Teegarden's Star d, orbits beyond the habitable zone and would have temperatures similar to the icy [[moons of Jupiter]]. Two longer-period [[Doppler spectroscopy|radial velocity]] signals were also detected; a 96-day signal corresponds to the star's rotation, while the origin of a 172-day signal is uncertain.<ref name="Dreizler2024"/>

According to one group of researchers, who were specifically studying this star, both habitable-zone planets could have maintained a dense atmosphere and so therefore there would be a high likelihood that at least one may harbour liquid water.<ref name="WandelTal-Or2019"/> However, another group of scientists, looking at Earth-sized planets in general in the habitable zones of stars, specifically in a likely [[tidal locking|tidally locked]] scenario, give Teegarden's Star b a 3% chance, and Teegarden's Star c only a 2% chance, of having even retained an atmosphere.<ref name="Rodriguez-Mozos_2019"/> 

Teegarden's Star b, c and d receive more X-ray radiation than Earth does, but if they have certain atmospheric compositions, as an Earth-like atmosphere, the effects on the ground would still be negligible.<ref name=Fuhrmeister2025/>

While [[Transiting Exoplanet Survey Satellite|TESS]] observations confirm that the planets of Teegarden's Star do not [[astronomical transit|transit]] their star as seen from Earth,<ref name="Dreizler2024"/> from 2044 to 2496 Earth would transit the Sun as seen from Teegarden's Star.<ref name="CARMENES"/>

{{OrbitboxPlanet begin
| table_ref = <ref name="Dreizler2024"/>
}}
{{OrbitboxPlanet
| exoplanet = [[Teegarden's Star b|b]]
| mass_earth = {{val|1.16|0.12|0.11|p=≥}}
| period = {{val|4.90634|0.00041}}
| semimajor = {{val|0.0259|0.0008|0.0009}}
| eccentricity = {{val|0.03|0.04|0.02}}
| inclination =
}}
{{OrbitboxPlanet
| exoplanet = [[Teegarden's Star c|c]]
| mass_earth = {{val|1.05|0.14|0.13|p=≥}}
| period = {{val|11.416|0.003}}
| semimajor = {{val|0.0455|0.0015|0.0016}}
| eccentricity = {{val|0.04|0.07|0.03}}
| inclination =
}}
{{OrbitboxPlanet
| exoplanet = d
| mass_earth = {{val|0.82|0.17|p=≥}}
| period = {{val|26.13|0.03|0.04}}
| semimajor = {{val|0.0791|0.0025|0.0027}}
| eccentricity = {{val|0.07|0.10|0.05}}
| inclination =
}}
{{Orbitbox end}}