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Friday, April 21, 2017

LHS 1140b - A Super-Earth in the Habitable Zone

We're getting our first good characterizations of terrestrial exoplanets lately. First, news broke of a possible planet around the nearest star to our Sun, Proxima Centauri. Then, we explored TRAPPIST-1, a mini solar system just 39 light-years away. Now, researchers from the Harvard-Smithsonian Center for Astrophysics announced the discovery today of a possible super-Earth orbiting an M-dwarf star just 34 light-years away. The discovery was published in the April 20th Nature.

An artist’s impression of exoplanet LHS 1140 orbiting a red dwarf star 41 light-years distant. ESO/SpaceEngine.org

LHS 1140b is a tantalizing find. It is cool, red host, LHS 1140, contains only 15% the mass of our Sun and is at least 5 billion years old. The planet passes in front of its star once every 15 days as seen from Earth. Jason Dittman (Harvard-Smithsonian Center for Astrophysics) and the team combined discovery data from the MEarth project with radial-velocity measurements from the High Accuracy Radial velocity Planet Searcher (HARPS) survey.

The high-resolution follow-up observations enabled researchers to calculate the planet's orbital parameters and physical characteristics to a high degree of precision: The super-Earth, containing between 4.8 and 8.5 times Earth's mass, orbits just 0.09 astronomical units from its primary (almost a quarter of the average distance between the Sun and Mercury). The planet spans around 1.4 Earths. Combine its mass and radius and you'll calculate an incredibly dense 12.5 g/cm3 — the planet has more than twice Earth's average density!

Though red dwarfs are often tempestuous flare stars — a strike against life on any orbiting worlds — they're also long-lived and miserly in terms of energy output. These cool stars are expected to shine for trillions of years, longer than the present age of the Universe. That's a plus in that it gives ample time to get the engine of evolution going.

Read Full Source Article at http://www.skyandtelescope.com/astronomy-news/welcome-lhs-1140b-super-earth-habitable-zone/

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