Science

Newly-discovered exoplanet twice the size of Earth could have water

Newly-discovered exoplanet twice the size of Earth could have water

It has also discovered a super-Earth and a rocky world, making three exoplanet discoveries in the first three months since it began surveying the sky in July. That's actually quite cool, considering how close the planet is to its star. Its discovery was announced by scientists at the annual American Astronomical Society meeting in Seattle.

"It's the coolest planet we know of around a star this bright".

HD 21749b also has the longest orbital period of any exoplanet found within 100 light years of us (36 days), is about three times Earth's size but 23 times its mass - and, perhaps surprisingly, it's considered nearly chilly, as exoplanets go.

Even though the Kepler spacecraft ceased operations months ago, after almost a decade in service, its legacy continues: Today, researchers announced that they have found a planet roughly twice as big as Earth, located within what could be its parent star's habitable zone.

However, it is unlikely that the planet is rocky and therefore habitable; it's more likely made of gas, of a kind that is much more dense than the atmospheres of either Neptune or Uranus.

This has already led to the discovery of two other planets, Pi Mensae c and LHS 3844b, back in September.

The Transiting Exoplanet Survey Satellite launched in April to take up the planet-hunting baton from the Kepler space telescope as that historic mission ended. The star is very similar to our sun, both in mass and in size. The announcement was made by scientists this week, and the new planet is called HD 21749b. This is relatively cool considering its proximity to its star.

An exoplanet three times the size of Earth has been discovered relatively close to our solar system. His team is now writing a proposal to NASA asking that TESS's mission be extended past its initial two years.




"Some of the most interesting science occurs in the early days of a supernova, which has been very hard to observe before TESS", said Michael Fausnaugh, a TESS researcher at the MIT Kavli Institute. NASA's Kepler space telescope which shut operations in October 2018, was the one to make these findings. Indeed, HD 21749b is very far-flung for TESS; two other smallish worlds found by the mission have orbital periods of 11 hours and 6.3 days, respectively.

TESS is surveying an area in the sky that is 400 times larger than what Kepler observed, including 200,000 of the brightest nearby stars.

TESS does this work by carving the sky up into overlapping sectors, studying each one for 27 days at a time. "We're only halfway through TESS's first year of operations, and the data floodgates are just beginning to open", he said. Its size is rare among exoplanets - planets beyond our solar system. Possible planets can be spotted by studying dips in light when the planet moves before its star.

Those researchers had also detected a signal, but they couldn't conclusively attribute it to a planet, Dragomir said.

Pi Mensae c is roughly twice Earth's size and can be seen in the Mensa constellation with the naked eye.

While impressive, it does not appear the planet has the attributes required to support life as a habitable world.

Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA's Ames Research Center in California's Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT's Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. Using ground-based telescopes, astronomers are now conducting follow-up observations on more than 280 TESS exoplanet candidates.