Exoplanets iron atmosphere, unusual orbit recorded in novel project

UniSQ researcher uses data from 1.5meter telescope for exoplanet observation in scientific first

A University of Southern Queensland PhD student has become one of the first scientists to characterise the atmosphere of a distant planet using data from a 1.5meter telescope.

Nataliea Lowson has recently published her findings on gas giant KELT-9b, an exoplanet so hot its atmosphere is made partly of iron and magnesium.

Atmospheric observations like this are made by analysing the wavelengths of light emitted as the planet orbits in front of its star. These can be difficult to record, with most measurements being made exclusively on space based or large aperture ground based telescopes.

Using data collected from a 1.5m ground based telescope and spectrograph set-up located in Arizona, Ms Lowson and her colleagues were able to determine KELT-9b’s atmospheric composition, which matched earlier observations outlined in the planet’s discovery paper.

“In theory, the bigger the telescope, the more light you can collect and therefore the more detail you can obtain about an object,” Ms Lowson said.

“Being able to do this science on a smaller telescope is a bit challenging, however it worked with KELT-9b because it’s a very hot planet, hotter than the surface of some small stars.

“It was cool to work with this data, which had been recorded back in 2014 and 2015, and receive such a positive result.”

The iron atmosphere isn’t KELT-9b’s only unusual feature according to Ms Lowson, with the planet also producing an uncommon orbital reading.

While most planets produce a standard U-shaped hydrogen alpha light curve, indicative of a regular orbit, KELT-9b instead produced a W-shaped reading.

Ms Lowson said the reason for this was still unknown, however she hypothesised the planet could possess a comet-like tail, which blocked the star’s light twice during orbit.

“It was certainly a surprise to discover the planet’s light curve reading was W shaped,” she said.

“In the end, the presence of a cometary tail was the model that best fit this unusual feature, however the circumstances needed to produce this are highly atypical.

“This recording and its analysis could help if the phenomenon is seen again in other exoplanets.”

Ms Lowson said learning about exoplanets gives us further insight into our own solar system.

“Similar to KELT-9b, we have found many stars that have Jupiter size planets orbiting close to the star – which prior to the first exoplanet discoveries in the 90s, we had previously thought of as being physically impossible,” she said.

“Finding these distant planets we thought couldn’t exist expands our knowledge and brings new questions – such as how did they get there and why aren’t they in our own Solar System?

“This experiment has helped to highlight the capabilities of small telescopes, and this method could be built on in the future to advance our understanding of these exoplanet systems.”

Learn more about the University of Southern Queensland’s astrophysics research.

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