2023-05-17 17:28:18
Saturn again takes the lead in the number of moons discovered around it, taking the lead with 145, vastly surpassing Jupiter, which has 92, according to the last count. This ‘sorpasso’ has been thanks to the discovery of 62 new satellites, which has also given a new record to the star-ringed planet: being the first world to exceed one hundred moons.
Over the past two decades, the surroundings of Saturn have been repeatedly surveyed with increasingly powerful technology in search of new and as yet undetected moons. In this latest research, the team including Edaward Ashton, a postdoctoral fellow at Taiwan’s Academia Sinica Institute of Astronomy and Astrophysics, used a technique known as ‘shifting and stacking’ to find fainter Saturnian moons (and therefore , smaller). The method has been used for lunar searches around Neptune and Uranus, but never for Saturn.
“Shifting a set of sequential images at the speed at which the moon moves across the sky results in an enhancement of the moon signal when all the data is combined, allowing moons that were too faint to see. in individual images become visible in the stacked image,” he explains in a announcement the University of British Columbia, where Ashton began the study.
The team used data taken with the Canada-France-Hawaii Telescope (CFHT) on top of Mauna Kea, Hawaii, between 2019 and 2021. By shifting and stacking many sequential images taken over three-hour periods, they were able to detect moons orbiting Saturn up to about 2.5 kilometers in diameter.
The team led by Ashton includes UBC Professor Brett Gladman, Mike Alexandersen (Harvard Smithsonian Center for Astrophysics), Jean-Marc Petit (Besancon Observatory) and Matthew Beaudoin (UBC).
The original discovery search was conducted in 2019 when Ashton and Beaudoin were students at UBC, and they discovered the moons in a meticulous search of the deep CFHT images acquired that year. But simply finding an object near Saturn in the sky is insufficient to say for sure that it’s a moon; it could not be an asteroid passing close to the planet (although this is unlikely).
To be absolutely sure, objects must be tracked for several years before they can be designated as orbiting the planet. After painstakingly matching objects detected on different nights over two years, the team managed to track 62 objects and confirm them as new moons.
Some of the team’s linked orbits were identified with previous observations from many years ago that briefly glimpsed some of these moons (but were not tracked long enough to establish their orbit around Saturn).
All new moons belong to the class of irregular moons, and are believed to have been initially captured by their host planet long ago. Irregular moons are characterized by their large, elliptical, and tilted orbits compared to regular moons. The number of known Saturnian irregular moons has more than doubled to 121, with 58 previously known before the search began. Including the 24 regular moons, there are now a total of 145 recognized by the International Astronomical Union.
Irregular moons tend to clump into orbital groups based on the inclination of their orbits. In the Saturnian system there are three such groups whose names are drawn from different mythologies: there is the Inuit group, the Gallic group, and the much more populous Norse group.
For example, three new discoveries fall into the Inuit group, with very small orbits inclined in a similar way to those of the previously known larger irregulars Kiviuq and Ijiraq. All new moons fall into one of three known groups, with the Nordic group again being the most populous.
A moon that broke
Clusters are believed to be the result of collisions, where the current moons in a cluster are remnants of one or more collisions on the originally captured moons. A better understanding of the orbital distribution provides insight into the collisional history of Saturn’s irregular system of moons.
“As one reaches the limits of modern telescopes, we find more and more evidence that a moderately sized moon orbiting backwards around Saturn was blown to pieces about 100 million years ago,” says Gladman.
Based on their previous studies of these moons, this team has suggested that the large number of small moons in retrograde orbits is the result of a relatively recent (in astronomical terms, within the last 100 million years) destruction of an irregularly-sized moon. moderate, now broken into the many fragments.
#Saturn #surpasses #Jupiter #breaks #record #number #moons