An exoplanet located at 212 lightyears away it is about the same size as Jupiter, but is ten times lighter. The discovery challenges our conceptions of how gas giants form and grow and the types of planets that can exist.
New research published in The Astrophysical Journal suggests that gas giants may emerge more easily inside a protoplanetary disk than before assumed. By “easier”, the authors of the new article, led by astronomer Björn Benneke and doctoral student Caroline Piaulet of the University of Montreal, mean that in some special cases, the embryonic nuclei needed to begin the formation of gas giants may be lighter than current models predict.
Benneke and Piaulet have just completed a four-year survey of WASP-107b, a gas giant with a mass in the range of Neptune But a radius the size of Jupiter. This gas giant was previously known to astronomers, but the group wanted to better understand such an object, with its end of low density, could have formed from its protoplanetary disk. These types of planets have been detected and studied before, earning nicknames such as “super-puff planets” and “cotton-caramel planets”.
This world it is very close to its host star, so a year on the WASP-107b lasts only 5.7 days. Using the Keck Observatory in Hawaii, the group attempted to improve estimates of the mass of the object. To do so, the team measured the degree to which the exoplanet shook its host star, a technique that astronomers call the method of radial velocity. Astronomers found that WASP-107b contains only 1.8 masses of Neptune, or 30 terrestrial masses. That means yes only a tenth of the mass of Jupiter, with a comparable waist. You can see where the cotton-candy comparison comes in.
G / O Media may receive a commission
The updated figure allowed the team to estimate the composition of the internal structure of the object. The core had to be heavy enough to prevent gas from escaping into space but light enough to maintain the extremely low density observed on the planet. Therefore, the solid core, according to scientists, can not be heavier than 4 Earth masses. In addition, 85% of the entire mass of the planet is packaged in the thick layer of gas that immediately surrounds the solid core, according to the document. In comparison, 5% 15% of Neptune’s mass is inside its thick layer of gas.
This was an unexpected result, as it is “significantly lower than what is traditionally supposed to be needed to trigger the massive accretion of the gas envelope,” as the authors wrote in their article (My Wife accusation of the opposite problem). In other words, the core of WASP-107b does not appear to have too much, and therefore gravitational influence, to facilitate the formation of a gas. giant inside the protoplanetary disk: the giant disk of dust and gas that surrounds a star during the process of planet formation. But, obviously WASP-107b exists, so our theories about these things must be wrong or at least they need refinement.
In fact, the new paper “addresses the fundamentals of how giant planets can form and grow,” Benneke said at the University of Montreal statement. “It provides concrete evidence that the massive accretion of a gas envelope can be triggered in much less massive nuclei than previously thought.”
Current models of gas giant formation are skewed toward the formation of Jupiter. and Saturn-like objects, and suggest that embryonic nuclei must be at least ten times heavier than Earth. Any lighter, and the nucleus is unable to collect or accumulate sufficient amounts of gas and dust before the dissipation of the protoplanetary disk. With the new data, researchers were forced to entertain alternative scenarios.
“For WASP-107b, the most plausible scenario is that the planet formed very far from the star, where the disk gas is cold enough for gas accretion to occur very quickly,” Piaulet said. in the statement. “Later, the planet was able to migrate to its current position, either through interactions with the disk or with other planets in the system.”
Interesting hypothesis, but that’s exactly it. Work will need to be done in the future to further validate this assumption.
During this research, the team encountered another exoplanet within the same stellar system, now called WASP-107c. Encouragingly, this planet — with an exaggerated orbit — suggests that Piaulet and his colleagues are on the right track with their proposed new training scenario.
The WASP-107c has about a third of Jupiter’s mass, so it is considerably heavier than its companion, the WASP-107b. This newly detected exoplanet takes three years to make a single orbit of its host star. This is not very interesting, but the elongated shape of its orbit is very large.
“The WASP-107c has kept in some respects the memory of what happened to its system,” Piaulet said. “Its great eccentricity hints at a rather chaotic past, with interactions between planets that could have caused significant displacements, such as the WASP-107b suspect.”
Nice, isn’t it? It’s always good to see corroborating evidence. Looking to the future, the team will try to better understand the chemical composition of WASP-107b, including its inexplicable lack of methane. Perhaps another clue to his strangeness? We will be interested to know.