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NASA, ESA, D. Jewitt (UCLA), Q. Ye (University of Maryland)
Images of the comet ATLAS from Hubble, taken on April 20 and 23
NASA / ESA’s Hubble Space Telescope provided astronomers with the clearest view yet of the comet C / 2019 Y4 (ATLAS) collapse. The telescope resolved approximately 30 fragments of the fragile comet on April 20 and 25 pieces on April 23.
The comet was first discovered in December 2019 by the ATLAS (Asteroid Ground Impact Ultimate Alert System) robotic inspection system in Hawaii, USA. USA It quickly increased in brightness until mid-March, and some astronomers initially predicted that it might be visible to the naked eye in May to become one of the most spectacular comets seen in the past two decades.
However, the comet abruptly began to weaken, leading astronomers to speculate that the ice core could fragment or even disintegrate. The fragmentation of ATLAS was confirmed by amateur astronomer José de Queiroz, who photographed around three fragments of the comet on April 11.
New observations of the comet’s fragmentation, made by the Hubble Space Telescope, obtained on April 20 and 23, reveal that the pieces are enveloped in a layer of comet dust, swept away by sunlight. These images provide further evidence that fragmentation of comets is probably common and may even be the dominant mechanism by which solid, icy nuclei of comets die.
“Its appearance changes substantially between the two days.so much so that it is quite difficult to connect the dots, “said David Jewitt of UCLA (University of California, Los Angeles), leader of one of the teams that photographed the doomed comet with Hubble.
“I don’t know if this is because the individual pieces flicker when they reflect sunlight, acting as bright lights on a Christmas tree, or because different fragments appear on different days.”
“This is really exciting – Both because these events are incredible to watch and because they don’t happen very often. Most fragmenting comets are too weak to see. Events on this scale only happen twice a decade, ”said Hubble’s second observation team leader Quanzhi Ye of the University of Maryland.
Considering that fragmentation of the comet occurs rapidly and unpredictably, reliable observations are rare. Therefore, astronomers remain very uncertain about the cause of the fragmentation. One suggestion is that the original core breaks into pieces due to the action of the jets that eject the ice by sublimation.
Since this flow is is not evenly dispersed by the comet, sharpens fragmentation. “A more detailed analysis of the Hubble data can show whether or not this mechanism is responsible,” Jewitt said. “Anyway, it is wonderful for Hubble to observe this dying comet.”
Sharp Hubble images can provide new clues to the separation. The telescope distinguished distinct pieces as small as a house. Before fragmentation, the entire core could not be greater than the length of two soccer fields.
The disintegrating comet ATLAS is currently within the orbit of Mars, at a distance of more or less 145 million kilometers from Earth when the last Hubble observations were made. The comet will make its closest approach to Earth on May 23 at a distance of approximately 115 million km and, eight days later, the Sun will pass 37 million km away.
