NASA's new planetary hunter has found his first alien world – a "super-Earth" that evaporates

Artist's illustration of the NASA's Exoplanet Monitoring Satellite (TESS).

(Goddard Space Flight Center of NASA)

A new study reveals that NASA's new research mission has detected its first alien world, a "super-Earth" that probably evaporates under the heat of its star.

The Exoplanets in Transit (TESS) satellite was launched into Earth orbit on April 18 on a SpaceX Falcon 9 rocket. The space telescope analyzes several hundred thousand of the brightest stars in the vicinity of the sun, to the search for tiny drops in brightness caused by the passage (or "transit") of planets in orbit as small as the Earth through the faces of these stars.

Scientists used the TESS data to discover a new planet around the star Pi Mensae, also known as HD 39091, located about 59.5 light-years from Earth in the constellation Mensa, Table. Pi Mensae is a yellow dwarf star like the sun and the second brightest among the stars known to have exoplanets in transit. [NASA’s TESS Exoplanet-Hunting Mission in Pictures]

Previous research had already spotted a gas giant around Pi Mensae that was about 10 times more massive than Jupiter. This exoplanet, named Pi Mensae b, has an "eccentric" orbit of very oval shape that carries it up to 3 astronomical units (AU) n of its star. (An AU is the average distance between the Earth and the Sun – about 93 million miles or 150 million kilometers.)

Now scientists have detected a new world around Pi Mensae – one about 2.14 times the diameter of the Earth and 4.82 times the mass of the Earth. This Super-Earth, nicknamed Pi Mensae c, revolves around 0.07 AU of its star, more than 50 times more than Mercury in the sun. (As the name implies, the superlands are slightly larger planets than ours, containing about 2 to 10 land masses.)

Pi Mensae is a super-Earth, a class of planets slightly larger and more massive than our own world.

The density of Pi Mensae c is consistent with an image where "the entire planet is made of water," said Space.com's chief author of the study, Chelsea Huang, of the Massachusetts Institute of Technology. However, "it is more likely to have a rocky core and an extended atmosphere of hydrogen and helium," she said. "We also think that this planet could evaporate at this moment, given the intense irradiation it receives from its host star."

Future research will study the strange configuration of the two known planets of Pi Mensae. The oval-shaped orbit of Pi Mensae b, similar to Jupiter, strongly contrasts with the circular orbit of Jupiter. This suggests that "something must have happened in the history of this planetary system to excite the orbit of the distant planet of Jupiter," said Huang. "If so, how did the internal system survive? These questions still require further research and their understanding will tell us a lot about the theory of planet formation."

TESS is following in the footsteps of NASA's famous Kepler Space Telescope, which has discovered about 70% of the 3800 exoplanets known to date, also using the transit method. TESS will surpass Kepler's exoplanets if all goes as planned, said TESS team members.

Scientists detailed their discoveries online Sept. 16 in an article submitted to The Astrophysical Journal Letters. You can read it on the arXiv.org online preprinting site.

Originally posted on Space.com.