The Universe is extremely vast, and also decidedly varied. So varied, that there are literally hellish places that go beyond our imagination. This is probably what makes astronomy so fascinating, that is, the fact that something new and incredible is always hidden behind the next star.
Kelt-9b is part of these decidedly curious worlds. This planet revolves around Kelt-9, a yellow star in the constellation of the Cygnus about 650 light years away. Its orbital radius is equal to just a thirtieth of the distance that separates the Earth from the Sun, so close that a year on Kelt-9b lasts only 36 hours! Because of its extreme proximity to its own, about 5 million km, this gaseous giant has a surface temperature of about 4,000 degrees.
These findings were made earlier by an American study, and were taken up by a team of scientists from the University of Geneva and the National Galileo Telescope (TNG) of the INAF, on the island of La Palma of Canarie. This new study, signed by Jens Hoeijmakers of the University of Geneva and other famous scientists including Emilio Molinari, director of the astronomical Observatory of the INAF of Cagliari (Italy), has been published in Nature.
Scientists first tried to simulate the planet’s atmosphere with sophisticated models, and the results showed that in the Kelt-9b atmosphere there could be gaseous iron, then atoms untied from any molecule. Later, using the Harps-N spectrograph supplied with the TNG, scientists actually observed the iron lines in the spectrum from the gas giant. But not only that, in fact, the lines of titanium were also evident!
At this point you may wonder how it was possible to observe the chemical composition of the atmosphere of a planet 650 light years away from us. In practice, when the planet passes in front of its star, part of the light is filtered by the atmosphere of the planet before arriving on Earth. During this passage, therefore, the star spectrum is modified and we can observe the spectral lines of the chemical species present in the planet’s atmosphere.
This discovery certainly gives a new meaning to the meaning of the expression “heavy air”: can you imagine an atmosphere of iron and titanium?
If you are curious, here is the link to the study on Nature: Atomic iron and titanium in the atmosphere of the exoplanet Kelt-9b.