Heat waves on Earth may be uncomfortable and even dangerous for some people, but our planet has nothing to do with the blazing hot world of WASP-76.
Astronomers have taken a deeper look at the exoplanet where temperatures soar to about 4,350 degrees Fahrenheit (2,400 degrees Celsius), hot enough to vaporize iron. In the process, the team identified 11 chemical elements in the planet’s atmosphere and measured their abundance.
It is remarkable that some of the rock-forming elements found on these distant planets have not yet been measured in the solar system’s gas giants Saturn and Jupiter.
“It’s very rare that an exoplanet hundreds of light years away can teach us something that would most likely be impossible to know about our own solar system,” the team leader and the University of Montreal Trottier Institute for Exoplanetary Research Ph.D. Stephen Pelletier he said in a statement. “That’s the case with this study.”
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Located about 634 light years away in the constellation Pisces, the strange planet WASP-76 b gets its extraordinary temperature from its proximity to its parent star. Classified as a “superhot Jupiter”, a massive planet found very close to its star, this exoplanet is about a dozen distances from its star, WASP-76, from Mercury to the Sun.
This gives WASP-76 b, which takes 1.8 Earth days to orbit its star, some other unusual properties. Although the planet contains about 85% the mass of Jupiter, it is about twice the width of the solar system’s gas giants and about six times its size. It is the result of intense radiation from its star “blowing” the planet.
WASP-76 b has been the subject of intense study since it was discovered as part of Wide Angle Planet Search Program (WASP) in 2013. This led to the classification of several elements in its atmosphere. Most notable was the 2020 discovery that iron evaporates on the tidally locked and constantly facing side of the planet to its relatively cooler “night side” which always faces space and condenses, falling as iron rain.
Encouraged by earlier investigations of WASP-76 b, Pelletier was inspired to obtain new observations of WASP-76 b using the high-resolution optical spectrometer MAROON-X on the Gemini North 8-meter telescope in Hawaii, part of the International Gemini Observatory. This allowed the team to study the formation of superhot Jupiters in unprecedented detail.
Because of WASP-76 b’s impressive temperature, elements that are normally rocky on terrestrial planets like Earth, such as magnesium and iron, vaporized and vaporized as gases into the planet’s upper atmosphere.
This means that studying these worlds can provide astronomers with unparalleled insight into the presence and abundance of rock-forming elements in the atmospheres of giant planets. This is impossible for a cooler giant planet like Jupiter because these elements are low in the atmosphere, making them impossible to detect.
What Pelletier and his colleagues found in their search for WASP-76 b is that the abundances of elements such as manganese, chromium, magnesium, vanadium, barium, and calcium closely match not only the abundances of these elements in their respective stars. , but also the amount. . Found in the sun.
The apparent initial abundance was not random. It is the result of hydrogen and helium being processed by successive generations of stars over billions of years. The star creates heavier elements until it uses up its fuel for nuclear fusion, and dies in a supernova explosion. This explosion released these elements into the universe, and they became the building blocks of later stars, with the remaining material surrounding these young stars as a protoplanetary disk, which, as the name suggests, could produce planets. This means that stars of the same age have a similar composition with the same abundance of elements that are heavier than hydrogen and helium, which astronomers call “metals”.
Because terrestrial planets like ours formed through more complex processes, they have a different abundance of heavy elements from their stars. The fact that the new study shows that WASP-76 b is similar in composition to its star means that it is also similar in composition to the disk of protoplanetary material that collapsed at its birth. And this probably applies to all giant planets.
However, not everything that has been discovered about the formation of WASP-76 b is predictable. The team found that several elements in Wasp-76 b’s atmosphere appeared to be “depleted”.
“The elements that appear to be lost in WASP-76 b’s atmosphere are actually elements that require a higher temperature to vaporize, such as titanium and aluminum,” said Pelletier. “Meanwhile, those that met our expectations, such as manganese, vanadium and calcium, all evaporate at slightly lower temperatures.”
The team interpreted this thinning as an indication that the composition of the gas giant’s upper atmosphere is sensitive to temperature. Depending on the temperature at which an element condenses, it will either be present as a gas in the upper atmosphere or be lost when it condenses into a liquid and sinks to the lower layers. From the lower atmosphere, the element is unable to absorb light which makes its “fingerprint” lost on observation.
“If confirmed, this discovery means that two giant exoplanets that have very different temperatures from one another could have two completely different atmospheres,” explains Pelletier. “Like a bowl of water, one of them is -1°C and freezes, and the other is liquid at +1°C. For example, calcium has been observed on WASP-76 b, but it might not work on slightly cooler planets.”
The team made another important discovery about WASP-76 b’s atmosphere; It contains a chemical compound called vanadium oxide. This is the first time these compounds have been seen in the atmosphere of a planet outside the solar system. This discovery will be of great interest to astronomers because vanadium oxide can have a significant impact on hot giant planets.
“This molecule plays a role similar to ozone in Earth’s atmosphere: it is very effective at heating the upper atmosphere,” explains Pelletier. “This causes temperatures to increase as a function of altitude, rather than decreasing as is typical on colder planets.”
The team also found a higher than expected nickel abundance around WASP-76 b, which may indicate that at some point in its history the gas giant planet swallowed a smaller Mercury-like Earth that is rich in the element.
The astronomers behind this discovery will continue to study this exoplanet and other similar worlds, trying to discover how temperature affects the composition of their atmospheres. In doing so, the team said they hoped some of what they had learned could be applied to giant planets that are closer to home.
The research is described in a research paper published Wednesday (June 14) in the journal alam.
2023-06-15 02:09:14
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