Kepler-62f

The super-Earth Kepler-62f was discovered in 2013. Its host star is about three billion years older than our Sun and the planet takes 267 days to make one complete orbit.

Its another planet thats 40% bigger than Earth, and likely rocky and it gets about 40% the amount of energy that we do, Coughlin says.

Kepler- 62f orbits around a K-dwarf star, which on average are much more massive than M-dwarfs. Its orbit is at a comparable distance from its star as Venus is to our Sun. Since the K-type star is cooler, the habitable zone is much closer. K-Dwarfs also have an extremely long lifespan, living somewhere around 30 billion years. Scientists think that -62f may be covered in water, but because its the farthest planet out in its system, it would require a pretty thick atmosphere to keep that water from freezing.

TRAPPIST-1 system

A family of three planets orbiting around TRAPPIST-1 were initially discovered in 2015. However upon studying the star more closely, they discovered that the star actually had seven different planets. The seven planets, TRAPPIST b, c, d, e, f, and g orbit around an ultra cool M-dwarf star and all fit within the orbit of Mercury and our sun. The TRAPPIST star is also only about the size of Jupiter, making it relatively small to host seven planets.

The neat thing about this one is that there are three planets that are in the habitable zone, so if you had one planet that had a catastrophic event and another planet had something wrong the odds of finding at least one of those three to be more Earth like is pretty good, says Coughlin.

One handy thing about having rocky planets close to one another like this is that if one is habitable then the accidental transport of life by comets or other impacts could pretty easily spread that life to the other bodies.

I was excited when they found this system with seven planets, and three in the habitable zone. This discovery changed my view that M-dwarfs are good places to look for potentially habitable planets mostly because you dont tend to have Jupiter-sized planets around M-dwarfs but you do tend to have rocky planets, Coughlin says.

M-dwarfs like TRAPPIST-1, Kepler-186 and Kepler-62 are extremely common in the galaxy and because of their long lifespans it makes it a bit easier to find them.

Whats next for the exoplanets?

Planets like -452b and -62f are the closest analogs to Earth, orbiting more Sun-like stars at a distance were more familiar with. The hunt for more Earth-like planets is ongoing, but the super earths are actually pretty hard to find because they orbit their star at a similar length of time that we do. Waiting a few years to to see if there's a dip in the light in front of the star is pretty challenging.

The Kepler mission had to stare at the same patch of sky for over four years to find planets like Earth, Coughlin says. The big planets close to their star around small stars are the easiest to find.

Go here to read the rest:

Your guide to the most habitable exoplanets - Astronomy Magazine