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‘Hellish’ new planet discovered

A University of Southern Queensland astronomer has found a fiery new planet.

With temperatures so hot that most metals would vaporise, a newly discovered world called TOI-1431b is one of the hottest planets ever discovered.

It is the latest find by a global team of astronomers led by Dr Brett Addison at the University of Southern Queensland’s Centre for Astrophysics in Toowoomba, Australia.

TOI-1431b, also known as MASCARA-5b, is located about 490 light-years away from Earth, and is about one and a half times larger and just over three times more massive than the Solar system’s largest planet, Jupiter. It orbits closely around a relatively bright and very hot star roughly every two and a half days.

Dr Addison, a University of Southern Queensland astrophysicist, said TOI-1431b was an extremely hot planet, even warmer than some red dwarf stars that are common in our Milky Way galaxy.

“It is a particularly interesting discovery as the host is one of the hottest stars with a transiting planet we’ve ever found, and because TOI-1431b is in such close orbit around its star, it's one of the hottest planets surveyed,” he said. 

“This is a very hellish world - dayside temperature of about 3000K (approximately 2700oC) and nightside temperature approaching 2600K (approximately 2300oC) – no life could survive in its atmosphere. In fact, the planet’s nightside temperature is the second hottest ever measured!

“These types of exceptionally hot planets, known as ultra-hot Jupiters, are quite rare.

“The discovery presents a great opportunity to study the atmospheres of these planets to understand how they form and migrate. TOI-1431b did not form that close to its star – it formed much further away and then migrated into this really tight orbit.”

Dr Addison said TOI-1431b was made even more unusual due to its retrograde orbit. 

“If you look at the Solar System, all the planets orbit in the same direction that the Sun rotates and they're all along the same plane. This new planet’s orbit is tilted so much that it is actually going in the opposite direction to the rotation of its host star,” he said.

TOI-1431b was first “sighted” by NASA’s Transiting Exoplanet Survey Satellite (TESS) as a planet candidate. Dr Addison’s follow-up observations and study using Stellar Observation Network Group (SONG) telescope in the Canary Islands, along with observations on other telescopes around the world, have since helped confirm the planet’s existence.

The University of Southern Queensland has an ongoing collaboration with the SONG team, with the University’s Mount Kent Observatory hosting three SONG telescopes to cover the skies in the Southern Hemisphere.

usq professor standing with space equipment
Astronomer Dr Brett Addison at the University of Southern Queensland’s Mount Kent Observatory (UniSQ Photography)