Super Earths Discovered Orbiting Nearby Red Dwarf Gliese 887

Super-Earths

Due to their low luminosity, observing individual red dwarfs is not an easy task.

It's also one of the closest stars to our sun, even though it's far from the reach of any spacecraft technology we have today.

"For the planets orbiting GJ 887, half of the planets would be in perpetual daytime and the other half in perpetual night time". Due to the gravitational pull exerted on the planet, tiny to and fro "wobbles" are created, which was measured by the scientists. They combined data from HARPS with measurements of the star-spanning for about 20 years.

The astronomers dubbed the planets Gliese 887b and Gliese 887c.

Based on their findings, astronomers say that two extrasolar planets have a short orbit, only 9.3 and 21.8 days.

However, follow-up studies need to confirm there is, in fact, a third promising planet orbiting the star.

Gliese 887b and Gliese 887c are considered super-Earths because they are larger than the Earth but still smaller than the ice giants Uranus and Jupiter.


But stars like these are cooler than the Sun, which means the habitable zone - the orbital band where temperatures are mild enough to allow liquid surface water - is much closer to GJ 887 in comparison with the Earth's distance from the Sun.

Gliese 887 is also dimmer and smaller than our Sun, meaning that the planets could get much closer to the star while still being potentially habitable. The two exoplanets were found to moving more rapidly than Mercury in our solar system.

"The planets are interior to, but close to the inner edge of, the liquid-water habitable zone", the researchers wrote in their study published in the journal Science.

In observing and studying the star, the researchers discovered some good news. According to the lead author of the study, Sandra Jeffers, "we've been looking for exoplanets orbiting Gliese 887 for almost 20 years, and while we saw hints of a planetary signal, it wasn't strong enough to convince ourselves that it was a planet".

The unusually quiet nature of Gliese 887 suggests that if it does possess a planet within its habitable zone, that world might have a greater chance at life than other red dwarf planets, which often erupt with unsafe flares.

If the star was as active as our Sun, it is likely that a strong stellar wind - outflowing material which can erode a planet's atmosphere - would simply sweep away the planets' atmospheres. "If someone had to live around a red dwarf, they would want to choose a quieter star like GJ 887", writes Melvyn Davies in a related Perspective. Davies was not involved with the study. This means that the newly discovered planets may retain their atmospheres, or have thicker atmospheres than the Earth, and potentially host life, even though GJ887 receives more light than the Earth. The telescope, expected to launch next year, can peer through the atmospheres of exoplanets and help characterize their compositions.

"These planets will provide the best prospects for more detailed studies, including the search for life outside our solar system", said Jeffers. This was followed in 2018 with the announcement of a super-Earth orbiting Barnard's star, the second closest star to the Sun.

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