2023-09-03 15:08:39
Discovered in 2019, the exoplanet TOI-1853b is astonishing: if its size is comparable to that of Neptune, its mass is enormous, twice as high as the masses of other planets of comparable size. A team of scientists proposes a model to explain this anomaly, according to which the planet would have formed following giant planetary impacts.
You will also be interested
[EN VIDÉO] The transit of the infernal exoplanet 55 Cancri e aka Janssen This video shows an artist’s impression of the super-Earth 55 Cancri e moving past…
In 2018, NASA launched its Tess space telescope (Transiting Exoplanet Survey Satellite), designed to detect exoplanets using the transit method. The latter consists of detecting periodic variations in the luminosity of a star, indicating the presence of a planet in orbit around it. By pointing the telescope at the star TOI-1853, an orange dwarf star located 542 light-years from our Sun, scientists in 2019 identified the presence of an exoplanet, dubbed TOI-1853b. It has amazing characteristics: with a size comparable to that of Neptune in our solar system, it is on the other hand almost seven times more massive. It defies everything we know regarding exoplanets of this size: it is twice as massive as the most massive exoplanet comparable in size to Neptune known to date. Its density is even higher than that of iron.
An exoplanet that shouldn’t be here
If the existence of such a dense exoplanet surprises scientists, its distance from its star is even more surprising. TOI-1853b completes a revolution around its star in just 30 hours (compared to a year for Earth), placing it in what astrophysicists call the ” hot neptune desert “. In this hot region close to a star, an exoplanet the size of Neptune should not exist. Radiation from the star would blow away the entire gaseous envelope of the Neptunian exoplanet, transforming it into a mini-Neptune (comparable to Neptune in composition but much smaller) or a super-Earth (if the entire gaseous envelope is evaporated and that only the solid core remains). Scientists do not know the exact composition of TOI-1853b, but they can thus deduce, from its distance from its star, that its mass is probably dominated by heavy elements. If the exoplanet defies what is known regarding the formation of Neptunian planets, a new studyconducted by scientists from the universities of Rome Tor Vergata and Bristol, proposes a scenario involving giant planetary impacts.
Giant impacts that would have blown the atmosphere of the young planet
According to the models of the authors of the study, the most plausible scenario indicates that the young TOI-1853b would have been much larger than it is today. Its initial composition would have been water-rich, with an atmosphere of light elements (hydrogen and helium) surrounding a rocky core rich in heavy elements. According to the model, it would then have resembled Jupiter, with a density slightly greater than that of water. But it would then have undergone several strong collisions with other planets, blowing its water and its atmosphere into space to leave only a rocky core, much denser. The idea is also not aberrant, when we know that planetary impacts have already taken place in our Solar System (leading for example to the formation of the Moon, according to the most commonly accepted theory). The scientists propose an alternative scenario, according to which TOI-1853b might have initially presented a strongly eccentric orbit (in the shape of an oval rather than a circle) before migrating towards its star, and having its atmosphere blown into the space.
The authors hope that their models can be taken into account in scenarios for the formation of other exoplanets, and will advance research on Neptunian planets and the “hot Neptune desert”. According to a recent studysuch formation scenarios are also explored to explain the formation of TOI-332b, another very massive Neptunian exoplanet.
—
Do not miss a single Futura magazine by subscribing! Enjoy the comfort of receiving your magazine directly in your mailbox, and at a preferential rate.
I DISCOVER THE LATEST ISSUE: HOW THE COSMOS INFLUENCES US?
By choosing our 1-year subscription offer, you will receive the next 4 issues of Mag’ Futura (148 pages to decipher the major challenges of today and tomorrow) for 1 year at only €4/month.
Futura is an independent and committed scientific media that needs its readers to continue to inform, analyze and decipher. To encourage this approach and discover our next publications, subscription remains the best way to support us.
1693755585
#amazing #exoplanet #shows #signs #giant #planetary #impacts
