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Following terrestrial binoculars, the Hubble Space Telescope has now also observed the disintegrated Comet ATLAS, making impressive shots of more than two dozen smaller nuclear fragments.
As reported, the disintegration of Comet ATLAS’s promising nucleus, which was predicted to be well visible to the naked eye in late May, began in early April, as indicated by its disintegration with ground-based telescopes into three larger pieces. The fragmentation of the comet’s nucleus has led to a decrease in its luminosity earlier than expected and, therefore, unfortunately, its very favorable observability, expected at the time of its proximity to the earth and the sun in late May, did not it happens. Comet ATLAS will be 116 million km (0.775 CSE) closer to our planet on May 23, and will be close to the sun on May 31, 37.8 million km (0.253 CSE) from our central star, within the Mercury’s orbit. Such a close proximity to the sun would have meant the comet’s increased dust and gas emission activity, and thus an increase in apparent brightness, if the nucleus of the original comet had remained attached. Here you can read a preliminary description of Krisztián Sárneczky’s comet ATLAS.
On April 20 and 23, the WFC3 camera of the Hubble Space Telescope (HST) took images of the comet ATLAS, more specifically of its observable central fragments, with a broadband optical filter in a UVIS2 channel that covers the visible range of the ultraviolet . The observations were made by two American astronomers, David Jewitt, a professor in the Department of Planetary Science and Astronomy at the University of California (UCLA, Los Angeles, CA) and Quanzhi Ye, a researcher in the Department of Astronomy at the University of Maryland (UMd, Greenbelt, Maryland). At the time of the sightings, the comet ATLAS was already walking within the orbit of Mars in the orbital section approaching its proximity to the sun, about 145 million km from the Sun. The following figure shows two of the images taken with HST April 20 and 23.
The observable seed fragments appeared in different positions in the images on April 20 and 23, and their number even changed: 30 on April 20 and only 25 on 23 – the smallest in 2-3 days. they broke into even smaller pieces, making them so weak that not even HST could see them. In addition, the smaller pieces showing degassing are subject to “rocket-like propulsion” by the gas leaving them, allowing them to move away from the spot seen in the first image.
With its WFC3 / UVIS2 camera on April 20, 2020. The size scale is 10 arcseconds, which corresponds to 8010 km at a comet distance. Celestial equatorial north (N) and east (E) and the direction of the Sun are indicated by an arrow (NASA, ESA, HST, D. Jewitt / UCLA, Q. Ye / University of Maryland)
The image of the seed fragments from Comet ATLAS taken with the HST on April 23 is shown in the figure below, which also shows a change in the position and appearance of the seed fragments compared to the image taken two days before.
With its WFC3 / UVIS2 camera on April 23, 2020. The size scale is 10 arcseconds, which corresponds to 7720 km at a comet distance. Celestial equatorial north (N) and east (E) and the direction of the Sun are indicated by an arrow (NASA, ESA, HST, D. Jewitt / UCLA, Q. Ye / University of Maryland)
As a reminder, some information about Comet ATLAS is worth remembering. Comet C / 2019 Y4 (ATLAS) was discovered in CCD images taken on the night of December 28 and 29, 2019 with a 0.5-meter ATLAS (Ultimate Ground Asteroid Impact Alert System) robotic telescope on top from Mauna Loa in the Hawaiian Islands. According to NASA’s JPL (Jet Engine Laboratory) orbital data, the comet orbits the Sun in a very elliptical orbit with a median axis greater than 310 CSE, an eccentricity of 0.99918 and an orbital plane at an angle of 45.3 degrees with with respect to the plane of the Earth’s orbit (ecliptic). It reaches 0.253 CSE during the day and 621 CSE during the day from our central star. The comet’s orbital period is 5,476 years (the previous orbital data corresponded to an orbital period of approximately 4,800 years).
The orbits of C / 2019 Y4 (ATLAS) and the 1844 “Great Comet” (C / 1844 Y1) are very similar, making it possible that the two celestial bodies are the remaining pieces of the disintegrated nucleus of a larger comet. . The common ancestor may have divided once near the Sun, within Mercury’s orbit, but may come from the distant Oort cloud and orbit near the Sun. These relatively “cool” comets, entering Mercury’s orbit, are very active and its seeds often disintegrate.
The Hubble Space Telescope was launched on April 24, 1990 with the American Discovery spacecraft, that is, just 30 years ago. This time around, the Hubble Space Telescope has aged its reputation again with another interesting observation, capturing stunning images of the fragments of the nucleus of the crumbled comet ATLAS.
The publication of the news was supported by the GINOP-2.3.2-15-2016-00003 project “Cosmic impacts and risks”.
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