Astronomers confirm 'exoplanet hell' with SAAO telescope

2019-05-31 06:53
An artist's impression of an exoplanet. (file)

An artist's impression of an exoplanet. (file)

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Astronomers have confirmed the existence of an exoplanet so hot, it can be described as hell.

Planet NGTS-4b, nick-named "The Forbidden Planet", was confirmed by researchers using the South African Astronomical Observatory's (SAAO) Sutherland High-speed Optical Cameras (SHOC) 1.0m telescope.

Temperatures on the planet exceed 1 000°C because it's close to its host star, in a region astronomers call the "Neptunian Desert".

It is the first exoplanet of its kind found in this hostile stellar zone and its temperature is hot enough to melt gold.

"This planet resides in a region very close to its host star, so close that the planet will receive very strong irradiation from the star, stripping the planet of its atmosphere," SAAO Science Engagement Astronomer Dr Daniel Cunnama told News24 on Thursday.

"So we don't expect to find a planet like this so close to a star. However, this planet still has a gaseous atmosphere and resides in this 'forbidden' region, meaning it probably moved in close to the star relatively recently, in the last million years or so."

READ: Bus-sized asteroid to whizz past Earth this weekend

Number of exoplanets

The planet orbits its star in 1.3 Earth days and is about three times the size of our home planet.

It was found by the method known as Transit Photometry.

Light from the star is measured and small dips in luminosity are detected as a planet passes between the star and observers on Earth.

"These planets are detected by observing stars brightness very regularly and looking for tiny dips in brightness as the planet moves in front of the star. SALT is not designed for this sort of work, however, the SHOC instrument on the 1.0m telescope is very good at this, and will certainly be involved in following up and detecting future planets around other stars," said Cunnama.

Planet NGTS-4b was first observed by the Next-Generation Transit Survey (NGTS) located in the Atacama Desert, Chile.

However, it was University of Leicester researcher Dr Matt Burliegh who confirmed the result, using the SHOC, at the Sutherland observatory in the Northern Cape.

"Since this transit is so shallow, NGTS-4b wasn't initially one of our top priority targets. But thanks to the excellent telescopes at SAAO in Sutherland, we were able to detect and confirm the transit, convincing ourselves the planet is real. We then set in motion many more observations to measure its mass and size," said Burliegh.

Astronomers have found nearly 4 000 exoplanets, and follow a strict procedure should they detect signs of life.

"The first and most important thing to do though would be to firstly independently confirm the source by requesting other telescopes to follow it up," said Cunnama.

Signs of life

The SETI Institute also advises that, once signs of life are confirmed by the scientific community, the secretary general of the United Nations should be informed in accordance with Article XI of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Bodies.

The public should be informed in a wide ranging, open and scientific manner, says SETI.

A planet orbiting in a star's habitable zone is regarded as having the best chance of having life.

According to, the closest such exoplanet so far is Proxima b which orbits in the habitable zone of star Proxima Centauri, 4.2 light years from Earth.

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