Gliese 436 is a red drawf in the constellation of Leo, that is 31.8 light-years distant (which is too faint to be seen by a naked eye). The star is orbting one known exoplanet Gliese 436 b, discovered in 2004, two sub-Earth canidates and a possible planet, Gliese 436 c.
Details[]
Gliese 436 is an M2.5V star as a red drawf. The sun's radius is about 42% from stellar models. The model also estimates that the outer atmosphere has a temperature of 3,318 K. Because of the temperature, it has an orange-red hue colour of an M-type star. Gliese 436 is older than the Sun several billion years and has a copious of heavy elements. Gliese 436 is also a member of the "old-disk population" in the Milky Way Galaxy.
Planetary system[]
Gliese 436 b[]
Gliese 436 is orbited by a known helium planet, Gliese 436 b. The planet has an orbit of 2.6 Earth days and transits the star. However, for Gliese 436 b, the transits enable the determination of the inclination, as they show that the planet's orbital plane is very nearly in the line of sight.
Possible second planet[]
A possible second planet, named as Gliese 436 c was claimed to be discovered with an orbit of 5.2 Earth days. The planet is thought to be a rocky, terristral planet. It was announced by Spanish scientists by analyzing its influence on Gliese 436 b's orbit. The existence of the planet is regarded as unlikely and retracted although scientists still say there's a possibility.
Two sub-Earths[]
In July 2012, NASA announced they believed they had observed a second planet, UCF-1.01 after the name of University of Central Florida. The radius was mesaured to have a radius two-thrids of Earth and having an Earth-like density, a mass of 0.3 times of Earth and a surface gravity of two-thirds of Earth. It orbits at 0.0185 AU from the star, every 1.3659 days. Another canidate is UFC-1.02, which is the same size, only one detected transit remained unknown. Hubble Space Telescope reanalysis were unable to comfirm the data.