Wednesday, 16 January, 2019

NASA Exoplanet Hunter Racks Up Bizarre Worlds and Exploding Stars

TESS Discovers Third New Planet Weird 'Sub-Neptune' Exoplanet Discovered by NASA Space Telescope
Sandy Nunez | 09 January, 2019, 10:27

NASA's Kepler Mission K2 team announced the discovery of another new world today, two months after the Kepler spacecraft ran out of fuel on October 30th, and ended its mission after nine years, during which it discovered 2,600 confirmed planets around other stars - the bulk of those now known - along with thousands of additional candidates astronomers are working to confirm.

This is the third new planet confirmed by the Transiting Exoplanet Survey Satellite (TESS) since its launch in April a year ago.

Of the planets yet discovered, HD 21749b has the longest orbital period around its star, taking 36 days to perform a transit. Those planets tear around their stars much more quickly than HD 21749b, completing orbits at 6.3 days and a meagre 11 hours. If confirmed, it could be the first Earth-sized world discovered by TESS.

The new world has a surface temperature of about 150 degrees Celsius, which scientists say is quite cool given how close it is to its star. Project member Diana Dragomir says that this is the coolest small planet known around a star this bright.

"We know a lot about atmospheres of hot planets, but because it's very hard to find small planets that orbit farther from their stars and are therefore cooler, we haven't been able to learn much about these smaller, cooler planets", she added. "If confirmed, it will be the smallest planet we have found to date", study co-author Chelsea Huang, a colleague of Dragomir's at the MIT Kavli Institute, said today during a briefing at the American Astronomical Society's winter meeting in Seattle. It's a "sub-Neptune" about three times bigger than Earth, which means it's likely gaseous rather than rocky.

Scientists said the system may hold an additional planet that is about the size of Earth that has an orbit of only eight days.

Scientists don't think that the planet is rocky, they believe that it is most likely made of gas of the sort that is much denser than the atmosphere of Neptune or Uranus, it's not believed to be habitable. They searched Kepler data for evidence of transits, the regular dimming of a star when an orbiting planet moves across the star's face.

The exoplanet, known as K2-288Bb, is about twice the size of Earth and orbits within the habitable zone of its star, meaning liquid water may exist on its surface. The new planet, K2-288Bb, orbits the smaller, dimmer star every 31.3 days.

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Tess monitors sections of the sky and waits for momentary dips in the light of about 200,000 nearby stars - a sign that a planet has passed in front of that star. "But we re-extracted the data and zoomed in to look more carefully, and found what looked like the end of a transit".

NASA has located a planet just outside of our solar system that may actually have water on it.

Image at the top of the page shows Kepler-10c, an Earth-like planet that's so large that astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) call it a "mega-Earth". "We don't know how that could form".

She and her colleagues compared the pattern to the first full transit they had originally discovered, and found a near flawless match - an indication that the planet passed again in front of its star, in a 36-day orbit. "But we were lucky and we caught the signals, and they were really clear".

Scientists are already working on followup observations for more than 280 planet candidates that TESS has found.

These exoplanets will be studied so that NASA can determine the best targets for future missions, like the James Webb Space Telescope.

"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 says.