WASP-107b, a super-Neptunian exoplanet about 212 light-years away in the constellation Virgo, harbors surprisingly low amounts of methane and a super-large core, according to two new papers published today in the journal Nature.
The artist's concept is based on recent data collected by the NASA/ESA/CSA James Webb Space Telescope, as well as previous observations from the NASA/ESA Hubble Space Telescope and other observatories, suggesting that exoplanet WASP-107b shows what it looks like. Image credit: NASA/ESA/CSA/Ralf Crawford, STScI.
WASP-107 is a highly active K-type main sequence star located approximately 212 light-years away in the constellation Virgo.
beginning discovered As of 2017, WASP-107b is one of the least dense known exoplanets, a type astrophysicists refer to as a “superpuff” or “cotton candy” planet.
This planet orbits very close to its star. It is more than 16 times closer to Earth than Earth is to the Sun, and its orbit is once every 5.7 days.
It has one of the coldest atmospheres of any exoplanet discovered, but at 500 degrees Celsius (932 degrees Fahrenheit) it is still significantly warmer than Earth.
This high temperature is thought to be the result of tidal heating caused by the planet's slightly non-circular orbit, and without resorting to extreme theories about how WASP-107b formed, it is unclear how This can explain how WASP-107b can expand so much.
“Based on its radius, mass, age, and assumed internal temperature, we believe that WASP-107b has a very small rocky core surrounded by a large mass of hydrogen and helium.” said Dr. Louis Wellbanks of Arizona State University, lead author of the paper.of first paper.
“But it has been difficult to understand how such a small core could kick up so much gas and stop it from fully growing into a Jupiter-mass planet.”
“If most of WASP-107b's mass was in the core, the atmosphere would have shrunk as the planet cooled over time after it formed.”
“Without a heat source to re-expand the gases, the Earth would be much smaller.”
“WASP-107b is a very interesting target for Webb because it is significantly cooler than many of the other low-density planets we have studied, hot Jupiters, and has a mass similar to Neptune,” the paper said. said lead author Dr. David Singh of Johns Hopkins University. Second sheet of paper.
“As a result, we should be able to detect methane and other molecules, providing information about their chemistry and internal dynamics that is not available from hotter planets.”
WASP-107b's huge radius, extended atmosphere and edge-on orbit make it ideal for transmission spectroscopy, a method used to identify different gases in exoplanet atmospheres based on how they affect the star's light.
Combining Mr. Webb's observations near infrared camera (NIRCam) and Mid-infrared measuring instrument (MIRI), Hubble's wide angle camera 3 (WFC3) Dr. Wellbanks and colleagues were able to construct a broad spectrum of light from 0.8 to 12.2 microns that is absorbed by WASP-107b's atmosphere.
Using the web near infrared spectrometer (NIRSpec), Dr. Sing and colleagues constructed an independent spectrum covering 2.7 to 5.2 microns.
The accuracy of the data makes it possible to not only detect but actually measure the abundance of abundant molecules such as water vapor, methane, carbon dioxide, carbon monoxide, sulfur dioxide, and ammonia.
Both spectra show a surprising lack of methane in WASP-107b's atmosphere. The amount is 1,000 times less than what you would expect based on the expected temperature.
“This is evidence that hot gas from deep within the planet must be mixing intensely with cooler layers in the upper layers,” Dr. Singh said.
“Methane is unstable at high temperatures. The fact that it was barely detected, while other carbon-containing molecules were, suggests that Earth's interior must be much hotter than we thought.” It shows that.
The source of WASP-107b's extra internal energy is thought to be tidal heating caused by its slightly elliptical orbit.
The distance between the star and the planet changes continuously during its 5.7-day orbit, and the gravity also changes, stretching and heating the planet.
Astronomers had previously proposed that tidal heating could be responsible for WASP-107b's bulge, but there was no evidence until Webb's results.
Once they established that the planet had enough internal heat to fully stir up its atmosphere, the researchers realized that the spectrum could provide a new way to estimate the size of the core.
“If we know how much energy exists on Earth, and if we know the proportion of heavy elements such as carbon, nitrogen, oxygen, and sulfur, and the proportion of hydrogen and helium on Earth, we can determine how much mass must exist on Earth. “We can calculate the nuclear power,” said Dr. Daniel Thorngren of Johns Hopkins University.
“The mass of the core turns out to be at least twice as large as originally estimated, which makes more sense from the perspective of how planets form.”
“Taken together, WASP-107b is no longer as mysterious as it once appeared.”
“Webb's data shows that planets like WASP-107b didn't have to form in such a strange way, with their tiny cores and huge gas envelopes,” said Dr. Mike Rhine of Arizona State University. It shows,” he said.
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L. Wellbanks other. High internal heat flux and large core in warm Neptune exoplanet. Nature, published online on May 20, 2024. doi: 10.1038/s41586-024-07514-w
DK Thing other. Warm Neptune's methane reveals the mixing of its core mass and active atmosphere. Nature, published online on May 20, 2024. doi: 10.1038/s41586-024-07395-z
Source: www.sci.news
