TRAPPIST-1 c

TRAPPIST-1c is a mainly rocky exoplanet orbiting around the ultracool dwarf star TRAPPIST-1, located away from Earth in the constellation Aquarius. It is the third most massive and third largest planet of the system, with about 131% the mass and 110% the radius of Earth. Its density indicates a primarily rocky composition, and observations by the James Webb Space Telescope announced in 2023 suggests against a thick CO2 atmosphere, however this does not exclude a thick abiotic oxygen-dominated atmosphere as is hypothesized to be common around red dwarf stars.

==Physical characteristics== ===Mass, radius, and temperature=== TRAPPIST-1c was observed with the transit method, which enabled scientists to calculate its radius. Transit-timing variations and computer simulations were able to determine the mass, density, and gravity of the planet. TRAPPIST-1c is the third-largest planet of the TRAPPIST-1 system, with a radius of . It is also the third-most massive of the system, with a mass of , slightly lower than that of the next most massive, TRAPPIST-1g. Initial estimates suggested that TRAPPIST-1c has a lower density (4.89 g/cm3) and gravity (0.966g) than Earth, consistent with a rock-based composition and a thick, Venus-like atmosphere. However, refined density estimates show that the planet's density is similar to Earth.