Tuesday, 11 December, 2018

Astronomers discover 'Super-Earth' planet that could support life

238746923-exoplanet-1 Artist's impression. Credit M. Weiss CfA
Theresa Hayes | 20 April, 2017, 06:00

This latest discovery comes within a year of the revelation that the nearest star beyond our sun, Proxima Centauri, is also orbited by an Earth-size planet, and less than two months after we learned the Trappist-1 system boasts a whopping seven such planets.

"There has been lots of debate about whether these planets can maintain a magnetic field (and if that's important for habitability) and if M-dwarf planets lose their atmospheres in their host star's active youth", principal investigator Jason Dittman of the Harvard-Smithsonian Center for Astrophysics told Astronomy. The scientists used the MEarth-South telescope array to monitor the brightness of the star LHS 1140, starting in 2014.

The first planet outside our solar system was discovered in 1995, but thanks to new techniques and especially NASA's planet-hunting Kepler telescope, the number of them has exploded in recent years. If either of those telescopes can't quite suss it out, future telescopes like the James Webb Space Telescope might make it easier. Astronomers say it's larger than Earth, but appears to be rocky and temperate and likely has an atmosphere.

The orbit is seen nearly edge-on from Earth and as the exoplanet passes in front of the star on each of its orbits it blocks a little of its light every 25 days.

In a paper detailing the discovery, the researchers also say they believe the planet has an atmosphere, adding that both star LHS 1140 and planet LHS 1140b are so close to Earth that "telescopes now under construction might be able to search for specific atmospheric gases in the future".

The newly discovered super-Earth LHS 1140b orbits in the habitable zone around a faint red dwarf star named LHS 1140, in the constellation of Cetus (The Sea Monster).

An global team of scientists has announced the discovery of a new "super-Earth" exoplanet (a planet with more mass than Earth, but not quite as big as our gas giants) that could represent our best chance of finding life outside of our solar system. That suggests the planet is dense enough to be rocky.

USA lead scientist Dr Jason Dittmann, from the Harvard-Smithsonian Centre for Astrophysics, said: "This is the most exciting exoplanet I've seen in the past decade".

Just because LHS 1140b shares a few key traits with Earth doesn't mean this planet is exactly like ours, though.

Further observations from the High Accuracy Radial-velocity Planet Searcher, or HARPS, led the researchers to estimate the planet's mass at 6.6 times that of Earth. HARPS also helped pin down the orbital period and allowed the exoplanet's mass and density to be deduced.

There might be another Earth out there, and its name is LHS 1140b. They are the most common stars in the Galaxy, making up 75% of its population of stars.

"It's just incredible what these amateurs are capable of", said Dittmann. And a good chunk of them also lie in the habitable zone. The Earth-sized planet Proxima b, which circles the star closest to our sun, might host water too. "We will need to learn about the planet's atmosphere before we can conclude on whether life could be harboured on the planet", Dittmann said.

"This is the first one where we actually know it's rocky", Charbonneau said. Other signs it could be habitable would be nitrogen molecules.

"With this discovery we have a world similar to Earth in some aspects, and dissimilar in some others", says Amaury Triaud of Britain's University of Cambridge, who was not involved with the research. And that means there's a better chance that this planet may be holding onto some valuable chemicals, like organic molecules and water. "We're essentially running down the list of the thing we want in a habitable planet and checking the boxes".