The USQ Mount Kent Observatory.
The USQ Mount Kent Observatory. Contributed

USQ researchers discover planet 'that could float on water'

UNIVERSITY of Southern Queensland researchers have discovered a new world, which like Saturn, is less dense than water and if placed in an ocean large enough would float.

While USQ researchers have been involved in many exoplanet discoveries, the discovery of TOI-257b is the first exoplanet confirmation led by the Toowoomba-based team using the Minerva-Australis facility at Mount Kent.

Lead author astrophysicist Dr Brett Addison said TOI-257b is about 250 light years away and transits a bright white star every 18 days.

It is likely a gaseous world, given its low density - with a mass forty times that of Earth, but a volume almost 350 times greater than our planet.

Dr Addison said the team followed up an initial detection of TOI-257b from NASA's Transiting Exoplanet Survey Satellite to confirm the exoplanet.

"This is a significant discovery, not just for USQ and Queensland, but as an example of cool and unusual planet types," Dr Addison said.

"TOI-257b is an example of what astronomers call 'sub-Saturns' (larger than Neptune and smaller than Saturn), a type of planet absent from the Solar System.

"The Universe is a quirky and diverse place, with broad classes of planet such as sub-Saturns, super-Earths and mini Neptunes that we don't have here at home.

"Warm sub-Saturns, like TOI-257b, are rare amongst the currently known exoplanets."

As the only dedicated 'exoplanet hunting' facility in the Southern Hemisphere, Minerva-Australis has played a key role in the confirmation discovery of 19 exoplanets, but TOI-257b marks the first Australian-led confirmation of planet detected by TESS.

Tracking exoplanets for NASA: Construction is complete on the Minerva Australis array of telescopes at USQ's Mt Kent observatory.
Tracking exoplanets for NASA: Construction is complete on the Minerva Australis array of telescopes at USQ's Mt Kent observatory.

"As of January, the TESS mission has delivered a total of 1604 planetary candidates and follow-up observations have resulted in a total of 37 confirmed planetary discoveries," Dr Addison said.

"It is likely that many more planets will be confirmed in the months to come, and Minerva-Australis will continue to play an important role.

"In fact, our data shows strong evidence for a second planet in the system, TOI-257c, which we hope to confirm in the coming year."

Minerva-Australis is funded by the Australian Research Council, USQ, and international partners including the Massachusetts Institute of Technology, George Mason University, University of Louisville, University of Florida, University of Texas, University of California, Riverside, and Nanjing University.

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