Oxygen found for the first time in an exoplanetary atmosphere

The finding was made on the distant exoplanet KELT-9b. Mind you, this is not a video hint.


Astrophysicists have reported in the journal Nature Astronomy the discovery of oxygen atoms  in KELT-9b , the first detection of this compound in an exoplanetary atmosphere.

With a daytime temperature of more than four thousand degrees, the exoplanet KELT-9b , discovered in 2017, is the hottest exoplanet known to date . It is a gas giant similar to Jupiter , with the difference that the temperature in its atmosphere is high enough to melt iron.

These extreme temperatures are due to the fact that it rotates very close to its host star, so much so that it completes an orbit in just about 36 hours. Since its discovery, it has sought to understand the nature of such a hot and peculiar object, as well as the reason why it does not disintegrate being so close to its star.

To study the atmospheres of these planets the method of transits is used, small eclipses produced when the planet passes in front of its star. During the transit, the light from the host star will pass through the planet’s atmosphere, making it possible to study the physical characteristics and composition of that atmosphere.

“Our team detected traces of atomic oxygen in the planet’s spectrum. Since KELT-9b is a very hot gas giant planet, this detection is not an indication of the presence of life, but it is the first definitive detection of oxygen atoms. in the atmosphere of an exoplanet, “says Francesco Borsa, a researcher at the Osservatorio Astronomico di Brera (INAF), who is leading the study.

The detection was possible thanks to a computer model developed by the scientific team, the most advanced for the study of the atmospheres of hot exoplanets developed to date. Not only did the model match previous observations of other compounds in KELT-9b’s atmosphere , it also predicted that the data should show the presence of oxygen atoms .

Detected thanks to a telescope in Spain

Thus, the team re-analyzed previous observations of the planet obtained with the 3.5-meter telescope of the Calar Alto observatory (CAHA, Almería, Spain), and their results confirmed the prediction of the model: the oxygen signals were there all the time, but they had not been detected by previous analyzes.

“The agreement between the model and the observations is a milestone in our exploration of planets outside the Solar System. It shows that we can now create realistic models of exoplanets and significantly improve our ability to understand the atmospheres of the hottest ones. Although it is not yet. It is possible to make similar observations of the atmospheres of smaller and cooler planets, one day it will be. We consider this work as a dress rehearsal for future work searching for oxygen in the atmospheres of different planets in the galaxy, including the smaller worlds, possibly habitable “, concludes in a statement Denis Shulyak, a researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who participated in the discovery.