The Earth’s atmosphere is not a uniform envelope, but consists of different layers, each of which has characteristic properties: for example, the lowest layer extending from sea level to the highest mountain peaks , the troposphere, contains most of the water vapor and where most weather events occur. The upper layer, the stratosphere, is the one that contains the famous ozone layer that protects us from the harmful ultraviolet radiation of the Sun. We know that it happens here, on our planet. But what about other worlds? Can they have a stratified atmosphere even though they are diametrically opposite to ours?
To find out, astronomers have just stepped into the atmosphere of one of the most extreme exoplanets ever discovered.
WASP-189b It is the first in which scientists have been able to investigate its different atmospheric layers, each with its own composition and chemical characteristics, similar to what happens on Earth. The conclusions of the study, carried out by researchers from the universities of Lund (Sweden) and Bern (Switzerland), have just published their conclusions in ‘
“In the past, astronomers often assumed that exoplanet atmospheres existed as a uniform layer and tried to understand it as such,” he explains. Jens Hoeijmakers, astronomerfrom Lund University. “But our results show that even the atmospheres of intensely irradiated gas giant planets have complex three-dimensional structures.”
WASP-189b belongs to one of the most intriguing categories of exoplanets: the hot jupiters. These extreme worlds are gas giants, like Jupiter, but in incredibly close orbits around their host stars, making one complete revolution around them in less than 10 days. Naturally, its temperatures are therefore scorching.
Scientists have long debated the reason for its existence: According to current models, a gas giant cannot form so close to its star, because gravity, radiation, and intense stellar winds should keep the gas from clumping together; however, of the nearly 5,000 exoplanets confirmed to date, more than 300 could be hot Jupiters. Learning more about these hellish worlds should reveal interesting insights into the dynamics of planetary systems.
Years lasting less than three days
WASP-189b, a unos 322 light years away, is among the most extreme worlds discovered to date. has approximately 1.6 times the size of Jupiter and its ‘years’ last 2.7 days (the time it takes to go around its star once). Its Sun is young and hot, causing WASP-189b’s surface to reach 3,200 degrees Celsius (5,792 degrees Fahrenheit) on its day side, making it hotter than some stars.
It is also one of the brightest transiting exoplanets known; that is, it passes between us and its star. In turn, that makes it very attractive for atmospheric studies. “We measure the light coming from the planet’s host star and passing through the planet’s atmosphere,” he explains. Bibiana Prinoth, an astronomer at Lund University, who led the research. “Gases in its atmosphere absorb some of the light from stars, similar to ozone absorbing some of the sunlight in Earth’s atmosphere, and thus leave their characteristic ‘fingerprint’. With the help of the HARPS instrument (High Accuracy Radial Velocity Planet Searcher) we were able to identify the corresponding substances.”
As is often seen on hot Jupiters, those gases included heavy metal vapors; specific, clouds of iron, titanium, chromium, magnesium, vanadium and manganese in gaseous state. Interestingly, the researchers also found traces of titanium oxide, which had never been conclusively detected in an exoplanet atmosphere before. Titanium oxide is rarely found in nature on Earth, but in WASP-189b, its presence could be helping to shape the atmosphere.
“Titanium oxide absorbs short-wave radiation, such as ultraviolet radiation,” says Kevin Heng, astrophysicist at the University of Bern. Therefore, its detection could indicate a layer in WASP-189b’s atmosphere that interacts with stellar radiation in a similar way as the ozone layer does on Earth.”
The researchers found another big clue that what they were indeed seeing were the exoplanet’s atmospheric layers. Elements in space are detected spectrally; that is, the light detected by the instruments is divided into the full spectrum and brighter or darker lines are sought. These indicate that something is amplifying or absorbing those wavelengths, which are called ‘ emission lines‘ The ‘absorption‘.
The absorption lines can then be traced to specific elements that we know absorb those wavelengths. But the absorption lines of WASP-189b they weren’t exactly where the researchers expected them to be. “We think that strong winds and other processes could drive these disturbances,” says Prinoth. “And because the fingerprints of different gases were altered in different ways, we think this indicates that they exist in different layers, similar to how fingerprints of water vapor and ozone on Earth would be altered in different ways. different from a distance, because they mostly occur in different atmospheric layers.”
The authors stress that life, at least as we understand it here, is not possible on WASP-189b. However, the research still has relevance to the search for life, as it represents a new milestone in probing exoplanetary atmospheres, which is where we are most likely to detect signs of extraterrestrial life. “I am often asked if I think my research is relevant to the search for life elsewhere in the Universe. My answer is always yes,” says Prinoth. This type of study is a first step in this search.”