One of the fluffiest exoplanets we have ever found in the Milky Way galaxy is how our understanding of giant planets is challenged.
It is called WASP-107b, orbiting an orange dwarf star 211 light years away, and was already known as one of the lowest density exoplanets, when its discovery was announced in 2017 was. A new analysis shows that the pleural planet is also strange compared to the astrophysicist.
This means that its core is much lower than initially calculated, a finding that could have huge implications for exoplanet research overall.
“This work explores how giant planets can form and evolve,” said astronomer Björn Beneke of the University of Montreal, Canada. “
“This provides solid evidence that large-scale accretion of the gas envelope can be triggered for cores that were thought to be much less massive.”
Super-puff planets, such as known low-density planets, are very rare and strange. They are the size of gas giants, but have very low density. WASP-107b is brilliantly puffy. Exoplanet is slightly smaller than Jupiter, but its mass is less than 10 percent of Jupiter’s, resulting in a density of only 0.13 grams per cubic centimeter.
Exoplanet is also close to its host star. It has an orbital period of only 5.7 days, so it is closed that its temperature is scorching 736 Kelvin (462 ° C, or 865 ° F), and its atmosphere is evaporating.
New research, led by physicist Caroline Piulet of the University of Montreal, first refined the mass of WASP-107b using four-year observations by the KAK Observatory to measure how the star responded to the gravitational tug of the orbiting exoplanet How much did I transfer to
Then, using this new calculation, the team conducted a detailed analysis of the structure of WASP-107b. To his great surprise, he found that the solid core of the exoplanet could be no more than about 4.6 times the mass of the Earth. This would mean that more than 85 percent of the exoplanet’s mass is in its pleural environment.
It is not so strange, by itself; Jupiter’s core is believed to be about 5 to 15 percent of the planet’s mass. But Jupiter is more massive overall, meaning its core is more massive, too. Jupiter is also far from its star. This raises many questions.
“How can a planet with such low density be there? And how did it keep its huge layer of gas from escaping, especially due to the planet being closer to its star?” Said Pilet. “This prompted us to conduct an in-depth analysis to determine the history of its formation.”
Until now, our understanding of the formation of gas giants has been based primarily on those we can study most easily: Saturn and Jupiter.
Both of these have a beak core 10 times larger than Earth’s mass, so astronomers thought that such a massive core gas is a prerequisite for massive construction. This provides the mass needed to trigger fugitive accretion and rapidly accumulate as much gas and dust as possible, before it is not sufficient in the protoplanary disk of the material orbiting the nascent star.
But there are clues in the WASP-107 system that point to a possible formation pathway for WASP-107b. Its low core mass can be one. The fact that the exoplanet is evaporating there indicates that it will be more difficult to form in its current close orbit.
And the team had another discovery. In his lengthy observations of the star, he found evidence of a second exoplanet – WASP-107c – far away, in the 1,088-day orbit. That orbit is also extremely eccentric, or oval in shape, suggesting a gravitational interaction with another body – perhaps a baby WASP-107b.
Astronomer Eve Lee of McGill University in Canada stated, “For WASP-107b, the most admirable scenario is that the planet is far from the star, where the gas in the disk is quite cold, which can cause gas emission very quickly. “
“The planet was later able to move to its current position, either through interactions with the disk or with other planets in the system.”
The team believes that WASP-107b is probably one of the best examples of an exoplanet that came extremely close to fugitive accretion before the process was interrupted, presumably by interaction with WASP-107c, which gave it the inside Used to flow.
This can make it an excellent exoplanet to study how large a core needs to be to trigger massive formation of gas. The team plans to revisit WASP-107b with more sensitive means to help solve this mystery.
“Exoplanets like WASP-107b that have no analog in our solar system allow us to understand the mechanisms of planet formation in general and the resulting diversity of exoplanets,” Piaulet said. “It inspires us to study them in great detail.”
The research has been published in The Astronomical Journal.