Physicists Get Unique View of Destroyed Comet

When C / 2019 Y4 ATLAS fragmented in April 2020, many were dismayed at the loss of what would have been the brightest comet since Hale-Bopp’s death in 1997. But NASA and the Solar Orbiter The European Space Agency just flew close to what’s left of ATLAS, giving scientists rare insight into what happens to a comet’s tail when it’s not tracking anything.

First observed in December 2019, ATLAS was on space agency radars for some time and would have been visible to the naked eye in May 2020, but it quickly became brighter in the previous month and collapsed before it could happen. The comet’s rupture was captured by the Hubble Space Telescope, which revealed a phantasmal glow from the pieces of the comet while they were still 91 million kilometers from Earth. The pieces are about the size of a house each, and together they look like the lighthouses of a submersible in deep water.

While the comet’s disintegration was a disappointment in some ways, the comet’s tail got stuck, so the Solar Orbiter was enlisted to check on what was left. (It was going to be in the area anyway, so it was a pretty handy run to do a run.) The search team took combined action of The remains of ATLAS yousing all of Solar Orbiter’s in-situ instruments: its energetic particle detector, magnetometer, radio and plasma wave experiment, and solar wind analyzer. Complete descriptions of the Solar Orbiter payload are available on the ESA website website.

Comets are best known for their iconic dust tail, which moves away from the nucleus. But the bodies also have ionic tails, which are generally weaker and come from comet gas interacting with the solar wind. the The Solar Orbiter magnetometer was vital to the team’s observations, as it takes measurements of local magnetic fields, allowing the team to see how the comet’s tail magnetic field interacted with the magnetic field carried through the solar system by the solar wind.

The model team developed from all this data indicated that the interplanetary magnetic field curves around the comet, and the central tail of the comet has a weaker magnetic field than its surroundings. You can think of the comet as a biker on a windy day: the solar wind curves around the comet. According to a press from the Royal Astronomical Society Release, the combination of the draping of the magnetic field and the ions produced by the comet fusion nucleus produces the ionic tail of the comet.

“This is a fairly unique event and an exciting opportunity for us to study the composition and structure of comet tails in unprecedented detail,” said Lorenzo Matteini, solar physicist at Imperial College. of London and responsible for recent works, in the same press release. . “I hope that with the Parker Solar Probe and Solar Orbiter now orbiting the Sun closer than ever, these events could become much more common in the future!”

Amateur astronomers certainly missed what would have been a spectacular sight last year. But their loss was the gain of the physicists, because they were able to better understand these strange phenomena.

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