Scientists Discover A New Exoplanet In The Neptunian Desert

New Exoplanet In The Neptunian Desert
Image credit: University of Warwick/Mark Garlick

Researchers discovered a new exoplanet which is smaller than Neptune but equipped with its own atmosphere. They found the planet in the Neptunian Desert, an area close to a host star where Neptune-sized exoplanets are not thought to be found. Because of its size and position in the star system, the researchers who made the discovery refer to it as “The Forbidden Planet.”

The new exoplanet in the Neptunian Desert was a joint discovery of researchers around the world, led by the University of Warwick. The authors of the study are Dr. Richard West, Professor Peter Wheatley, Dr. Daniel Bayliss and Dr. James McCormac at the Astronomy and Astrophysics Group at the University of Warwick. They identified the exoplanet at the Next-Generation Transit Survey (NGTS). Their findings were published in the journal Monthly Notices of the Royal Astronomical Society.

The NGTS is a wide-field photometric survey used to detect Neptune-sized or smaller exoplanets as they orbit their respective stars. The facility is situated at the European Southern Observatory’s Paranal Observatory in the Atacama Desert in Chile. It was built by the U.K.’s University of Warwick, University of Leicester, Cambridge University and Queen’s University Belfast in collaboration with the Observatoire de Genève, DLR Berlin and the Universidad de Chile.

Because the exoplanet was discovered by researchers at the NGTS, they officially named it NGTS-4b, although they also refer to it as “The Forbidden Planet” because it’s smaller than Neptune but three times bigger than Earth. It weighs about 20 Earth masses and has a radius that’s 20% smaller than Neptune.

The planet is a scorching 1,000 degrees Celsius, and its orbit lasts only 1.3 days, compared to the 365 days it takes for the Earth to complete one trip around the sun. Researchers say this planet is the first one of this kind to be found in the Neptunian Desert. That’s because host stars emit a lot of radiation, which makes it impossible for planets with gaseous atmospheres to retain their gases without having them evaporate, leaving nothing but a rocky core.

The planet was found using the transit method, which means researchers look for blockages of light from the star caused by a planet passing by it. Ground-based telescopes can usually pick up blockages of 1%. However, the NGTS can detect a dip of only 0.2%, which is far more advanced.

Because the planet has its own atmosphere, researchers believe it moved to the Neptunian Desert just recently, possibly within in the last million years. The other explanation could be is that the planet was extremely big and that its atmosphere will keep evaporating until it’s gone.

“This planet must be tough—it is right in the zone where we expected Neptune-sized planets could not survive. It is truly remarkable that we found a transiting planet via a star dimming by less than 0.2% – this has never been done before by telescopes on the ground, and it was great to find after working on this project for a year,” West said in a statement. “We are now scouring out data to see if we can see any more planets in the Neptune Desert—perhaps the desert is greener than was once thought.”