Published: Wed, January 09, 2019
Sci-tech | By April Francis

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

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

"It's a very exciting discovery due to how it was found, its temperate orbit and because planets of this size seem to be relatively uncommon", said Adina Feinstein, a University of Chicago graduate student in astrophysics and lead author of a paper describing the new planet that was accepted for publication by The Astronomical Journal.

Experts still aren't sure whether the planet hosts life, but say if plants were transferred there, they would likely survive. Because TESS stares non-stop at one slice of the sky for 27 days, then moves to a neighbouring slice, it captures an unprecedented view of these exploding stars as they brighten and then dim.

Less than a year after NASA's TESS spacecraft was launched, the scientists behind the mission have unveiled their third confirmed planet, a weird alien world that's between Earth and Neptune in size.

A year ago at the American Astronomical Society meeting, it was announced that citizen scientists helped discover five planets between the size of Earth and Neptune around star K2-138, the first multiplanet system found through crowdsourcing.

How a small inner planet stays on that path as a bigger planet lurches on an elliptical orbit around the same star is a mystery.

"We think this planet wouldn't be as gaseous as Neptune or Uranus, which are mostly hydrogen and really puffy", Dragomir said.

It is the third confirmed exoplanet sighted by TESS, with the first being Pi Mensae c, roughly twice Earth's size and visible to the unaided eye in constellation Mensa. Those planets tear around their stars much more quickly than HD 21749b, completing orbits at 6.3 days and a meagre 11 hours.

"We've confirmed three planets so far, and there are so many more that are just waiting for telescope and people time to be confirmed", Dragomir said. "So it's going really well, and TESS is already helping us to learn about the diversity of these small planets". "But we re-extracted the data and zoomed in to look more carefully, and found what looked like the end of a transit".

During the first month of data collection, TESS captured images of six supernovae, said Michael Fausnaugh, another researcher at the MIT Kavli Institute.

The finding comes from data from NASA's Kepler space telescope, which ran out of fuel in October 2018. This will enable scientists to survey almost the entire sky. Observing just one sector of the sky once it began science operations, researchers announced at AAS that TESS has already identified six supernovae - a remarkable finding.

There will be more opportunities for citizen scientists to help discover exoplanets.

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

The exoplanet, called K2-288Bb, is within its star's habitable zone, which means liquid water could exist on its surface. There were too many light curves to study on their own.

He continued: "Re-orienting Kepler relative to the Sun caused minuscule changes in the shape of the telescope and the temperature of the electronics, which inevitably affected Kepler' sensitive measures in the first days of each campaign". That telescope, launching in 2021, would be able to characterize the details and atmospheres of exoplanets in ways scientists have not been able to do.

Even if TESS records the looked-for pattern of dimming and brightening, astronomers have to make ground-based observations to confirm that what they're seeing is truly an exoplanet rather than some other type of phenomenon.

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