‘Hot Neptune’ outer planet its atmosphere was found to contain sulfur dioxide; This atmosphere also erupts into space as the planet rotates over its star’s poles in a steeply inclined orbit every three and a half days.
Presence of sulfur dioxide in the atmosphere of the exoplanet called GJ 3470b, ranked 96th light years from SoilHe was shocked when he was noticed by James Webb Space Telescope (JWST).
“We didn’t think we’d see sulfur dioxide on planets this small, and it’s exciting to see this new molecule in a place we didn’t expect because it gives us a new way to understand how these planets form.” Thomas Beatty of the University of Wisconsin, Madison said: expression. “And minor planets are particularly interesting because their composition really depends on how the planet formation process occurs.”
Everything about the GJ 3470b tells us that it has a fascinating and eventful history.
Planets It forms in a disk of gas and dust that orbits a plane aligned with the star’s rotation axis. ours solar systemWe can see evidence of this disk on all planets. Mercury with Neptune orbit in the ecliptic plane. GJ 3470b, on the other hand, follows a path with a cold axis inclined at 89 degrees to the rotation axis. red dwarf star. In other words, it is on a steep orbit passing over the poles of the star. Planets do not usually form in such orbits.
Relating to: Why are there so few ‘hot Neptunian’ exoplanets?
Its mass is 13.9 times larger mass of earthand about 40% in diameter Jupiter’s, GJ 3470b is an inflated gas bag. When such worlds are close to their stars, astronomers call them ‘hot Neptunes.'” GJ 3470b’s atmospheric temperature is 325 degrees Celsius (617 degrees Fahrenheit); Neptune in our solar system has a temperature of -200 degrees Celsius (-330 degrees Fahrenheit).
Current models of planet formation explain how gas giants usually form farther from their stars rocky planets, at colder depths where gas is more abundant. But GJ 3470b orbits only 5.3 million kilometers (3.3 million miles) from its star. For comparison, Mercury, the closest planet to us sunAlthough red dwarf systems are generally diminutive compared to our solar system, they orbit at an average distance of 58 million kilometers (36 million miles) from our star.
Normally, we would expect GJ 3470b to form earlier and move inward later, as a result of its interaction with the planet-forming disk of its star. Meanwhile, scientists would normally suspect that Earth is being pushed out of its orbital plane by a gravitational interaction with another planet, or perhaps even by disturbance caused by a nearby star.
But the planet’s atmospheric mix suggests otherwise.
Although JWST detects molecules such as sulfur dioxide, GJ 3470b’s atmosphere consists of a higher proportion of hydrogen and helium than even the gas planets in our solar system. Hubble space telescope In 2019. Well explanation put forward It is possible that GJ 3470b actually formed close to its star as a rocky planet before forming a thick atmosphere of almost pure hydrogen and helium, but at present this is just a hypothesis. That’s why JWST’s detection of sulfur dioxide is so important, because its presence can help distinguish between different theories of how the planet formed.
The detection of sulfur dioxide came to light thanks to the passage of GJ 3470b through its star; This allows astronomers to perform what is 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 starlight, leaving dark absorption lines in the star’s spectrum.
But these absorption lines are difficult to reveal, especially for hot Neptune, which is likely covered in a featureless haze.
“The thing is, everyone looks at these planets, and most of the time everyone sees straight lines,” Beatty said. “But when we looked at this planet, we didn’t really see a straight line.”
Instead, JWST was able to confirm absorption lines from 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 concerned the atmospheres of hot Jupiter, where temperatures exceed a thousand degrees Celsius (1,830 degrees Fahrenheit).
“The discovery of sulfur dioxide on a planet as small as GJ 3470b gives us another important item on the list of ingredients for planet formation,” Beatty said.
The team believes that sulfur likely started as a component of hydrogen sulfide. However, because GJ 3470b orbits so close to its star, ultraviolet light from the star’s body creates a pulse strong enough to easily shatter atmospheric molecules, leading to a type of chemical mess consisting of fragmented molecular components recombining with other components. atoms and molecules. A sulfur atom combines with two oxygen atoms to form sulfur dioxide.
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But the planet’s parent star doesn’t just break down atmospheric molecules; The hydrogen released from these molecules could completely remove them from the planet. GJ 3470b is therefore literally volatile Before our eyes, the stellar wind is slowly blowing its atmosphere away. spaceleaving behind a stream of hydrogen gas. The planet has already lost an estimated 40% of its original mass.
According to Beatty, the presence of sulfur dioxide in its atmosphere, the unexplained tilted orbit, and the mass loss that has dramatically changed GJ 3470b forever are important clues to the origin of this weird and wonderful planet.
“These are important steps in the recipe that created this special planet and may help us understand how planets like it are made,” he said.
Beatty presented the results at the 244th meeting of the American Astronomical Society on June 10, and they were accepted for publication in Astrophysical Journal Letters.