Image: artist’s rendering of KELT-9b orbiting its star./MPIA
The search for some trace of life outside our planet and, even more, our Solar System, is the center of the target for space research in the 21st century. However, most of the exoplanets that have been detected so far are inhospitable and totally incompatible with life.
Therefore, any clue of chemical elements that could make up organic matter, or the conditions to sustain it, excites astronomers.
Now scientists have found iron and titanium for the first time in the atmosphere of a planet outside the vicinity of our star. The discovery has been made on the planet KELT-9b, which is, on the other hand, the hottest extrasolar world ever discovered.
This sweltering exoplanet, located about 620 light-years away from Earth in the constellation Cygnus, is what astronomers call an ultrahot Jupiter ; even hotter than most stars. But it is much larger than the giant in our Solar System: it is three times the mass of Jupiter and twice its diameter.
Its high temperature is due to the fact that it orbits very close to its star, KELT-9.
A ‘Jupiter ultrahot’
Specifically, the term Jupiter ultrahot is used to designate planets with temperatures exceeding 1,700 degrees Celsius. The astrophysicist at the University of Bern and participant in the study describing the conditions of this planet, Kevin Heng, explained to Space.com the following: “These types of planets are so hot that they look like stars, even if they are planets, and that can reach temperatures of up to 4,000 degrees Celsius “.
And it was precisely this record-breaking heat that allowed astronomers to detect iron and titanium in KELT-9b’s atmosphere.
Although iron is one of the most abundant elements in the universe, it is difficult to detect in cold environments, since atoms are trapped between other molecules. But the high temperatures of KELT-9b allowed the iron not to condense in the atmosphere, and thus atoms of iron and other metals can scatter.
Titanium atoms have also been detected in KELT.9b; Although titanium has been found outside the Solar System before, it is the first time that this element has been found in its atomic form.
The previous findings were, specifically, of titanium dioxide (a molecule made up of one titanium atom and two oxygen atoms) in the atmosphere of an exoplanet called Kepler-13A.
An almost chance discovery
The discovery of these elements has occurred on the planet almost by chance. The research team looked at one-year data collected by the Galileo National Telescope on La Palma, Spain, looking for hydrogen, when they discovered the existence of iron and titanium. These observations are obtained by analyzing the spectrum of light that is produced after an object passes in front of its star.
It is unlikely that Heng’s team will find signs of life on KELT-9b, but now their goal is to draw up a complete chemical inventory of the planet, in which, the researchers estimate, “there should be violent storms, and other metals as well.” .
The study has been published by the journal Nature .
Reference:
H. Jens Hoeijmakers, David Ehrenreich1, Kevin Heng. ‘Atomic iron and titanium in the atmosphere of the exoplanet KELT-9b’. Nature (Aug. 15, 2018). Doi.org/10.1038/s41586-018-0401-y
