There is no one like him. It is a tremendously fluffy planet. The mass of the nucleus of the giant exoplanet WASP-107b is much less than what was thought necessary to build the monstrous gas envelope that surrounds giant planets like Jupiter and Saturn, according to a team of astronomers from the University of Montreal, Canada. ). This finding therefore challenges our understanding of how giant planets form.
The planet in question, categorized as ‘cotton candy’ because of its low density, is orbiting an orange dwarf star 211 light years away from Earth and, although it was discovered in 2017, a new survey of the world has shown that the planet it is much bulkier than astronomers initially thought.
According to the study published in The Astronomical Journal and thanks to observations obtained by the Keck Observatory in Hawaii, the planet WASP-107b orbits its star 16 times closer than Earth to the Sun. It is so close that its orbital period is only 5.7 days and its temperature of about 461 ºC , reason why its atmosphere is evaporating quickly. In addition, it is as big as Jupiter, but with only a tenth of its mass.
What is its density?
The researchers’ estimates suggest that it has a fairly low density; Its core has a mass of at most about four Earths, and the remaining 26 Earth masses are found in its swollen atmosphere. That is, more than 85% of its mass represents a gaseous envelope (for comparison, Neptune only has 5-15% of the mass in its gas layer.
Experts say this discovery has “big implications” for what we understand about how giant planets form and grow.
“This work addresses the very foundations of how giant planets can form and grow. It provides concrete evidence that a massive build-up of a gas envelope can be triggered for nuclei that are much less massive than previously thought,” explains Caroline Piaulet, from the Exoplanet Research Institute (iREx) and co-author of the work.
How could a planet with such low density be formed?
Most gas giant planets, such as Jupiter and Saturn, have a solid core at least 10 times more massive than Earth, but this planet appears to have a solid core no more than four times the mass of Earth , according to the authors. . Actually, these low-density planets are quite rare and strange.
“For WASP-107b, the most plausible scenario is that the planet formed far from the star, where the gas in the disk is cool enough that the accumulation of gas can occur very quickly,” added Eve Lee, co-author of the job. “Later, the planet was able to migrate to its current position, either through interactions with the disk or with other planets in the system.”
Astronomers hope to collect new observations of this fascinating planet once the long-awaited James Webb telescope launches in October this year.
Referencia: “WASP-107b’s density is even lower: a case study for the physics of gas envelope accretion and orbital migration,” Astronomical Journal (2021). DOI: 10.3847/1538-3881/abcd3c
