A ‘hot Neptune’ exoplanet It has been discovered that there is sulfur dioxide in the atmosphere – an atmosphere that also spews into space as the planet orbits its star in a steeply inclined orbit every three and a third days.
The existence of sulfur dioxide in the atmosphere of the exoplanet, named GJ 3470b and located at 96 light years by Soilcame as a shock when it was noticed by the James Webb Space Telescope (JWST).
‘We didn’t think we’d see sulfur dioxide on such small planets, and it’s exciting to see this new molecule in a place we didn’t expect, because it gives us a new way to find out how these planets formed ,” sThomas Beatty of the University of Wisconsin, Madison said in a rack. “And small planets are especially interesting, because their compositions really depend on how the planet formation process occurred.”
Everything about the GJ 3470b tells us that it has a fascinating and eventful history.
Planets form in a disk of gas and dust that swirls around a plane aligned with a star’s axis of rotation. In our solar systemwe can see the evidence of this disk in that all the planets come from Mercury Unpleasant Neptune orbit in the ecliptic plane. GJ 3470b, on the other hand, follows a path inclined 89 degrees to the rotation axis of its cool red dwarf star. In other words, it is in a steep orbit that passes over the star’s poles. Planets do not typically form in such orbits.
Related: Why are there so few ‘hot Neptune’ exoplanets?
With a mass 13.9 times greater than The mass of the Earthand a diameter of about 40% that of Jupiter, GJ 3470b is an inflated gas bag. When such worlds are close to their star, astronomers call them “hot Neptunes.” GJ 3470b has an atmospheric temperature of 325 degrees Celsius (617 degrees Fahrenheit); the temperature of Neptune in our solar system is –200 degrees Celsius (–330 degrees Celsius). Fahrenheit).
Current models of planet formation describe how gas giants typically form further from their star then rocky planets, in the cold depths where gas is more abundant. Yet GJ 3470b orbits at a distance of only 5.3 million kilometers from its star. For comparison: Mercury, the closest planet to us Sunorbits at an average distance of 58 million kilometers (36 million miles) from our star, although red dwarf systems are typically smaller compared to our Solar System.
Normally, we would expect GJ 3470b to have formed further outward and then migrated inward due to interactions with its star’s planet-forming disk. Meanwhile, scientists would normally suspect that the world might have been pushed out of the orbital plane via a gravitational interaction with another planet, or perhaps even by a disturbance caused by a nearby passing star.
However, the planet’s atmospheric mix suggests otherwise.
Despite the JWST’s detection of molecules in it, such as sulfur dioxide, GJ 3470b’s atmosphere remains composed overwhelmingly of hydrogen and helium, more so than the gas planets in our solar system – a fact noted by the researchers. Hubble Space Telescope in 2019. So the explanation put forward is that GJ 3470b actually formed close to its star as a rocky planet before developing a thick atmosphere of almost pure hydrogen and helium – but at this point this is just a hypothesis. That’s why the JWST’s detection of sulfur dioxide is so important, because its presence could help distinguish between different theories of how the planet formed.
The detection of sulfur dioxide came to light thanks to GJ 3470b passing through its star, allowing astronomers to perform so-called ‘transmission spectroscopy’. As light from its parent star shines through GJ 3470b’s atmosphere, molecules in the world’s atmosphere absorb some of the star’s light, leaving dark absorption lines in the star’s spectrum.
However, it is difficult to detect these absorption lines, especially for a hot Neptune that is likely covered in a featureless haze.
“The thing is, everyone looks at these planets and often everyone sees flat lines,” Beatty said. “But when we looked at this planet, we didn’t really get a flat line.”
Instead, the JWST was able to confirm absorption lines of carbon dioxide, methane and water vapor and indeed detect sulfur dioxide in the region for the first time. time. This actually makes GJ 3470b the lightest and coldest exoplanet known to have sulfur dioxide in its atmosphere. Previous detections involved the atmospheres of hot Jupiters with temperatures above a thousand degrees Celsius (1830 degrees Fahrenheit).
“Discovering sulfur dioxide on a planet as small as GJ 3470b gives us another important item on the list of ingredients for planet formation,” Beatty says.
The sulfur probably started out as a component of hydrogen sulfide, the team thinks. However, because GJ 3470b orbits so close to its star, the ultraviolet light from the stellar body has a powerful enough effect to easily break apart atmospheric molecules, leading to a kind of chemical churn formed by broken molecular components that reassemble combine with others atoms and molecules. A sulfur atom combines with two oxygen atoms to form sulfur dioxide.
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However, the planet’s parent star doesn’t just break down atmospheric molecules; hydrogen released from those molecules can completely remove them from the planet. So GJ 3470b is literal evaporate before our eyes the stellar wind gradually blows in its atmosphere room, leaving a stream of hydrogen gas. The planet has already lost an estimated 40% of its original mass.
The presence of sulfur dioxide in the atmosphere, the inclined orbit that remains unexplained, and the mass loss that dramatically changes GJ 3470b forever are important clues to the origin of this strange and beautiful planet, according to Beatty.
“These are important steps in the recipe that created this particular planet and could help us understand how such planets are made,” he said.
Beatty presented the results at the 244th meeting of the American Astronomical Society on June 10, and they have been accepted for publication in Astrophysical Journal Letters.