First detection of oxygen in an exoplanetary atmosphere

A team of scientists, including the Spanish Institute of Astrophysics of Andalusia (IAA-CSIC), has participated in the first discovery of oxygen atoms in the atmosphere of a planet outside the solar system and the hottest known.

Since the discovery of the first planet outside our solar system in 1995, more than 4,000 extrasolar planets have been detected.

Throughout these two decades, scientific teams from around the world have tried to characterize their atmospheres and explain why these new worlds are so different from the planets of the solar system.

Now the team has published in the magazine “Nature Astronomy” the finding of oxygen atoms in DATE 9b, the first detection of this compound in an exoplanetary atmosphere.

With a daytime temperature of more than 4,000 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 the traces of atomic oxygen in the spectrum of the planet. 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 ”, said this Wednesday researcher Francesco Borsa.

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.

The model not only matched previous observations of other compounds in the atmosphere of DATE 9bIt also predicted that the data should show the presence of oxygen atoms.

The team went back to studying previous observations of the planet obtained with the 3.5-meter telescope at the Calar Alto observatory in Almería (southeastern Spain), and their results confirmed the model’s prediction: the oxygen signals were there all the time, but they had not been detected in previous analyzes.