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5 mins read 12 May 2021

A planet hot enough to vapourise metal confirmed by USQ researchers

 A global team of astronomers, led by University of Southern Queensland research fellow, Dr Brett Addison have discovered a new ultra hot Jupiter, a type of planet defined by its extreme temperature and the exceptionally close orbit of its star.  

Astronomer Dr Brett Addison at the University of Southern Queensland’s Mount Kent Observatory Credit - USQ

University of Southern Queensland (USQ) research fellow, Dr Brett Addison has used information from NASA’s Transiting Exoplanet Survey Satellite (TESS) to confirm the existence of TOI-1431b / MASCARA-5b, an ultra-hot Jupiter. 

The newly confirmed planet is over 490 light-years away and according to Dr Addison it is “so hot that most metals would melt or even vaporise.”

Dr Addison described TOI-1431b as a “hellish world” saying that no life would be able to survive in its atmosphere. Much like the Gas Giants (Jupiter and Saturn) and Ice Giants (Uranus and Neptune) in our own Solar system, TOI-1431b doesn’t have any solid surface, he went on to say.

To obtain data on TOI-1431b, the Multi-site All-Sky CAmeRA (MASCARA) was used, which consists of two separate stations and is operated by Leiden University, in The Netherlands. 

One station is located on the Island of La Palma in the Canary Islands and the other is at the ESO La Silla Observatory in Chile. It was the La Palma facility that originally identified TOI-1431b as a potential exoplanet. 

However, it was Dr Addison and his team that used the information from both the MASCARA and TESS images to confirm TOI-1431b was indeed an exoplanet, and in fact an ultra-hot Jupiter. 

“I could slowly start to see an orbit ... forming in the data, and as we collected more and more data I could see ‘OK this is definitely a planet’,” he said.

Harsh, Hot Exoplanets

TOI-1431b has a retrograde orbit around its Star. Artist impression of TOI-1431b in orbit (Credit - Ethen Schmidt, University of Kansas ESA / ATG Medialab / CC BY-SA 3.0 IGO. Image modifications by Brett Addison, USQ)

There are exoplanets known as Hot Jupiters and then there are others which are known as Ultra Hot Jupiters. An Ultra Hot Jupiter is defined as having a dayside temperature greater than 2200K. At that temperature, these hot planets have surfaces that are hotter than some of the coolest stars in the galaxy. With a dayside temperature in excess of 2900K and a nightside temperature in excess of 2500K, TOI-1431b is believed to be one of the hottest of these kinds of planets ever detected. 

According to Dr Addison, “these types of exceptionally hot planets, known as Ultra Hot Jupiters, are quite rare,” in fact there are only around 16 currently known planets that fall into this category. 

“It is extremely hot, but it also orbits one of the hottest stars that has a planet, and this happens to be one of the brightest stars that host a transitioning planet”, said Dr Addison. 

The temperature is not the only thing that the researchers are finding interesting about TOI-1431b and planets like it.

“It is really interesting, we can study the atmosphere of these planets, understand how these planets form and migrate, because this planet didn’t form that close to its star. It formed much further away and then migrated into this really tight orbit,” said Dr Addison. 

TOI-1431b is also massive, in fact it is around one and a half times larger, that of our own Solar system's largest planet, Jupiter and is just over three times its mass. 

It also has a retrograde orbit, which is how a planetary orbit is described when the planet appears to go backwards around its star. “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,” said Dr Addison. 

Transiting Exoplanet Survey Satellite - T.E.S.S.

Illustration of NASA's Transiting Exoplanet Survey Satellite - TESS. Observing an M dwarf star with orbiting planets. Credit - NASA

The Transiting Exoplanet Survey Satellite or TESS is part of a project to search for planets outside our solar system. By detecting a tiny change in the visible light emitted by a star as a potential planet crosses between the star and the satellite, TESS can identify potential planets. TESS looks for these “shadows” with it’s extremely sensitive detectors that sit behind its four cameras that can pick up these, sometimes tiny, “dips” in stellar brightness. 

Launched in 2018 TESS looked at the Sun’s nearest 200,000 stars during its initial mission looking for planet candidates, which took just over two years. TESS is the successor to K2 and Kepler missions that discovered over 2600 planets outside our solar system and ended in 2018. 

So far TESS has captured evidence of more than 2200 potential planets orbiting bright nearby Stars. Whilst it’s primary mission has been completed it is now in a wide orbit between the Earth and Moon, filling in the gaps, covering both the Northern and Southern hemispheres. 

The paper is now available on the preprint server, arXiv.org