The Teegarden's Star Exoplanetary System
Teegarden's Star is a star with 0.09 times the mass of the Sun, and 0.11 times its radius. It is located 12.49 light years away from the solar system and is estimated to be 8 billion years old, as compared to the Sun which is roughly 4.6 billion years old.
Teegarden's Star is known to have 2 exoplanets in orbit around it.
Teegarden's Star b
Teegarden's Star b was discovered by the Calar Alto Observatory observatory using the radial velocity method. Its discovery was announced in 2019-06. Its semi-major axis is 0.03 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 4.91 Earth days to complete an orbit around its host star, Teegarden's Star.
Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0, which means that when Teegarden's Star b is at is at its closest point to its host star, 0.03 astronomical units separates the two, and when it is at its farthest point, this number is 0.03. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.
The mass of Teegarden's Star b is 1.05 times the mass of Earth. At less than 1.5 Earth masses, Teegarden's Star b is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.