Some worlds out there in the Universe are so strange that they make our Solar System planets seem almost insignificant.
Super-Mercuries mini-NeptunesFor instance, it challenges expectations about planetary development. There’s also the Hot Jupiters; and, of course, the super-hot Jupiters. These are worlds so near to their host stars their atmospheres are dense with heavy elements and clouds, vaporized with extreme heat.
Astronomers have now found the heavy metal in two of the most extreme worlds in the Milky Way. In the atmospheres of exoplanets WASP-76b and WASP-121b drift clouds of barium – the 56th element on the periodic table.
Previous searches had previously found vanadium dioxide, calcium oxide, and titanium dioxide in the atmosphere. WASP-76bWASP-121b’s atmosphere contains iron, vanadium, iron and chromium. This iron could even rain down on the horizon at night in a storm nobody would want to sing.
Barium wafting through high altitudes at high altitudes elevates the entire shindiggery.
“The paradoxical and counterintuitive question is: why is there so much heavy matter in the upper atmospheres of these planets?” says astronomer Tomás Azevedo Silvaof the University of Porto and of Institute of Astrophysics and Space Sciences, (IA), in Portugal.
“We weren’t expecting or looking specifically for barium and had to verify that it was indeed coming from the planet, as it hadn’t been seen before on any other exoplanet.”
It is difficult to figure out the chemistry in an exoplanet’s atmosphere. First, we need an exoplanet to pass between us, its host star, in what is known as transiting. The planet must then pass often enough to amplify the signal and gather sufficient data. An atmosphere thick enough for light to pass through the planet is necessary.
Absorption alters the wavelength of light and alters the electromagnetic spectrum seen from the star. Scientists can determine the spectral fingerprints and chemistry of exoplanets by comparing their transits with the light emitted by stars.
It’s fiddly, painstaking work, but rewarding – it can help us better understand the diversity and evolution of exoplanets in the wider galaxy. Particularly for ultra-hot Jupiters. These gas giants, which are mysterious and incredibly close to their star, are way too close to form there. The gravity, radiation, intense stellar winds, and strong stellar winds should have prevented the gas from clumping together.
Astronomers can piece together the history of these worlds by figuring out their composition and future.
WASP-76b WASP-121bBoth orbit very close to their stars with orbital periods of 1.8 Earth days and 1.27 Earth day, respectively. They are also very chunky, with masses 1.18 and 0.92 times those of Jupiter. This makes barium detection very unique.
“Given the gravity of the planets we would expect heavy elements such as barium to rapidly fall into the lower layers. says astronomer Olivier Demangeon, also of University of Porto IA. ”At the moment, we are not sure what the mechanisms [for its presence] are.”
It will take some more research to find the answer to this puzzle, but the team has given us more information from their work on the exoplanets. They detected cobalt, strontium and possibly titanium in WASP121b’s atmosphere and confirmed previous detections.
In addition, they were able to confirm features of WASP-121b that indicate that its atmosphere is leaking – the exoplanet is being evaporated by its star. This is yet another sign that hot Jupiters cannot survive for long periods of time so close to a star.
Some elements are highly ionized, giving planetary astronomers plenty to chew on.
“The presence of these heavy-ionized species at high elevations in the atmospheres super-hot Jupiters might be an indication of unanticipated atmospheric dynamics.” Researchers write in their paper.
This paper cannot be used to explain the mechanism of the presence of these species within the upper layers of our atmosphere. We hope this discovery will encourage atmospheric modeling.
The research was published in Astronomy & Astrophysics.
