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

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

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

The Transiting Exoplanet Survey Satellite (TESS) has discovered a planet orbiting the star HD 21749, which lies about 53 light-years from Earth in the faint constellation Reticulum, scientists announced today (Jan. 7).

The new exoplanet, named HD 21749b, was discovered by NASA's Transiting Exoplanet Survey Satellite (TESS), which launched in April. Those planets tear around their stars much more quickly than HD 21749b, completing orbits at 6.3 days and a meagre 11 hours.

Astronomers have discovered a planet twice the size of Earth, and it's within a zone that could allow liquid water to exist on its surface.

The new planet's surface reaches about 300℉, which, according to the MIT Kavli Institute for Astrophysics and Space Research, is "relatively cool", considering the proximity to its star, which is nearly as bright as our Sun.

This year, Kevin Hardegree-Ullman, postdoctoral scholar in astronomy at the California Institute of Technology, announced that the Spitzer space telescope followed up on that discovery and discovered a sixth planet, K2-138 g, smaller than Neptune, that orbits the star every 42 days. It's very hard to find small planets that orbit farther from their stars, and are therefore cooler. "But here, we were lucky and caught this one and can now study it in more detail".

K2-288Bb is half the size of Neptune or 1.9 times the size of Earth, placing it in the "Fulton gap " between 1.5 and two times the size of Earth. Surprisingly, it is also a whopping 23 times as massive as Earth.

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.

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

Johanna Teske, a Hubble fellow and co-author of the report, said: "I'm very interested to know whether [it] has an Earth-like density to match its Earth-like radius - this will contribute to our understanding whether Earth-sized planets have diverse compositions or are all roughly similar to Earth".

The researchers also detected hints of another, smaller planet in the system, a planet that would have an orbital period of 7.8 days.

Three new planets and six supernovae outside our solar system have been observed by Nasa's planet-hunting Tess mission in its first three months. The satellite will spend the first year surveying the sky in the Southern Hemisphere, before swiveling around to take in the Northern Hemisphere sky.

In May 2017, citizen scientists began discussing a particular planet candidate, but it had only two transits, or passes of the planet in front of its star. TESS found as many in its first month.

Examining data from the fourth observing campaign of Kepler's K2 mission, the team noticed two likely planetary transits in the system. "But we had this one transit, and knew something was there".

As it turned out, though, the team wasn't actually analyzing all of the data. "But we re-extracted the data and zoomed in to look more carefully, and found what looked like the end of a transit". "But we were lucky and we caught the signals, and they were really clear". Those researchers had also detected a signal, but they couldn't conclusively attribute it to a planet, Dragomir said.

The discoveries of a new planet and several supernovae are exciting enough and what's to come should give us even more information about the phenomena already discovered.

Feinstein and Makennah Bristow, an undergraduate student at the University of North Carolina Asheville, worked as interns at NASA's Goddard Space Flight Center, searching the data for transits. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.