# The LP 791-18 Exoplanetary System

LP 791-18 is a star with 0.14 times the mass of the Sun, and 0.17 times its radius. It is located 86.40 light years away from the solar system and is estimated to be 0.5 billion years old, as compared to the Sun which is roughly 4.6 billion years old.

LP 791-18 is known to have 2 exoplanets in orbit around it.

## LP 791-18 b

LP 791-18 b was discovered by the Transiting Exoplanet Survey Satellite (TESS) observatory using the transit method. Its discovery was announced in 2019-09. Its semi-major axis is 0.01 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 0.95 Earth days to complete an orbit around its host star, LP 791-18.

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 LP 791-18 b is at is at its closest point to its host star, 0.01 astronomical units separates the two, and when it is at its farthest point, this number is 0.01. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.

The mass of LP 791-18 b is 1.27 times the mass of Earth. The radius of LP 791-18 b is 1.12 that of Earth. At less than 1.5 Earth masses, LP 791-18 b is a regular terrestrial planet, much like the terrestrial planets we find in our solar system, namely Mercury, Venus, Earth and Mars.