Sutherland observatory makes find
Pivotal in discovery of ‘Forbidden Planet’
THE SA Astronomical Observatory’s (SAAO) 1.0m telescope in Sutherland has been pivotal in the discovery of what has been called a “Forbidden Planet”.
SAAO provided crucial follow-up observations in new research published recently by members of the Astronomy and Astrophysics Group at the University of Warwick in the UK, detailing the discovery of an exoplanet in the so-called “Neptunian Desert”.
The planet NGTS-4b, nick-named ‘The Forbidden Planet’ by researchers, is about 20 times the mass of Earth and three times the size. The planet orbits its host star in just 1.3 days with temperatures exceeding 1000°C.
It is the first exoplanet of its kind to have been found in the Neptunian Desert, the region close to stars where, up until now, no Neptune-sized planets have been found.
NGTS-4b was first noticed using the state-of-the-art Next-Generation Transit Survey (NGTS) observing facility, designed to search for transiting planets on bright stars.
The NGTS is at the European Southern Observatory’s Paranal Observatory in the heart of the Atacama Desert in Chile.
The discovery relied heavily on follow-up observations made by Dr Matt Burleigh at the University of Leicester using the Sutherland Highspeed Optical Cameras on the SAAO 1.0m Telescope in November 2017.
This triggered an international
Since this transit is so shallow, NGTS-4b wasn’t initially a priority target Matt Burleigh University of Leicester
effort to obtain further observations and a few weeks later it was confirmed that the transit was indeed a subNeptune exoplanet.
When looking for new planets astronomers look for a dip in the light of a star – this is the planet orbiting it and blocking the light.
Usually, only dips of greater than 1% are picked up by ground-based searches, but the NGTS telescopes can pick up a dip of just 0.1%.
With a dip almost that small, this exoplanet is, by a long way, the shallowest transiting planet ever discovered by a ground-based survey (the transit is less than 0.2%).
“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,” Burleigh explained.
“We then set in motion many more observations to measure its mass and size.”