A ‘Forbidden’ exoplanet has been found in the ‘Neptunian Desert’

Subject: A ‘forbidden’ Neptunian (possibly rogue) exoplanet - Comments and suggestions are welcome! Don't hesitate and leave a comment on our comment section down below the article!

Artist impression of the ‘Forbidden’ exoplanet - Image Credit: University Warwick

A Neptunian exoplanet has been found in what should be a ‘Neptunian Desert’ by telescopes run by the University of Warwick in an international collaboration of astronomers. The found planet might actually be a rogue planet!

New research, led by Dr Richard West including Professor Peter Wheatley, Dr Daniel Bayliss and Dr James McCormac from the Astronomy and Astrophysics Group at the University of Warwick, has identified a rogue planet.

NGTS is situated at the European Southern Observatory's Paranal Observatory in the heart of the Atacama Desert, Chile.  It is a collaboration between UK Universities Warwick, Leicester, Cambridge, and Queen's University Belfast, together with Observatoire de Genève, DLR Berlin and Universidad de Chile.

NGTS-4b, also nick-named ‘The Forbidden Planet’ by researchers, is a planet smaller than Neptune but three times the size of Earth.

It has a mass of 20 Earth masses, and a radius 20% smaller than Neptune, and is 1000 degrees Celsius. It orbits around its host star in only 1.3 days – the equivalent of Earth’s orbit around the sun of one year.

This is the first exoplanet of its kind to have been found in the so called Neptunian Desert.

The Neptunian Desert is the region close to a star where no Neptune-sized planets are found.  This area receives strong irradiation from the star, meaning the planets do not retain their gaseous atmosphere as they evaporate leaving just a rocky core. However NGTS-4b still has its atmosphere of gas.

When looking for new planets astronomers look for a dip in the light of a star (the so called transit method of finding exoplanets) – this the planet orbiting it and blocking the light. Usually only dips of 1% and more are picked up by ground-based searches, but the NGTS telescopes are a bit better at this and are able to pick up dips of just 0.2%

A simulated view of Jupiter’s transit of our sun, as seen from another star - Image Credit: Tomruen via Wikimedia Commons

A simulated view of Jupiter’s transit of our sun, as seen from another star - Image Credit: Tomruen via Wikimedia Commons

Researchers believe that the planet may have moved into the Neptunian Desert recently (in the last one million years or so) or it might be very big and its atmosphere is still evaporating.

Dr Richard West, from the Department of Physics at the University of Warwick comments:

“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.

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.”

Source: University of Warwick press release - Further reading: full paper

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