Planets Red dwarf

artist s conception of red dwarf, common type of star in sun s stellar neighborhood, , in universe. although termed red dwarf, surface temperature of star give orange hue when viewed close proximity.

many red dwarfs orbited exoplanets, large jupiter-sized planets comparatively rare. doppler surveys of wide variety of stars indicate 1 in 6 stars twice mass of sun orbited 1 or more jupiter-sized planets, versus 1 in 16 sun-like stars , 1 in 50 red dwarfs. on other hand, microlensing surveys indicate long-orbital-period neptune-mass planets found around 1 in 3 red dwarfs. observations harps further indicate 40% of red dwarfs have super-earth class planet orbiting in habitable zone liquid water can exist on surface. computer simulations of formation of planets around low mass stars predict earth-sized planets abundant, more 90% of simulated planets @ least 10% water mass, suggesting many earth-sized planets orbiting red dwarf stars covered in deep oceans.

at least 4 , possibly 6 exoplanets discovered orbiting within gliese 581 planetary system between 2005 , 2010. 1 planet has mass of neptune, or 16 earth masses (m⊕). orbits 6 million kilometers (0.04 au) star, , estimated have surface temperature of 150 °c, despite dimness of star. in 2006, smaller exoplanet (only 5.5 m⊕) found orbiting red dwarf ogle-2005-blg-390l; lies 390 million km (2.6 au) star , surface temperature −220 °c (56 k).

in 2007, new, potentially habitable exoplanet, gliese 581c, found, orbiting gliese 581. minimum mass estimated discoverers (a team led stephane udry) 5.36 m⊕. discoverers estimate radius 1.5 times of earth (r⊕). since gliese 581d, potentially habitable, discovered.

gliese 581c , d within habitable zone of host star, , 2 of candidates habitability of exoplanets discovered far. gliese 581g, detected september 2010, has near-circular orbit in middle of star s habitable zone. however, planet s existence contested.

on 23 february 2017 nasa announced discovery of 7 earth-sized planets orbiting red dwarf star trappist-1 approximately 39 light-years away in constellation aquarius. planets discovered through transit method, meaning have mass , radius information of them. trappist-1e, f , g appear within habitable zone , may have liquid water on surface.