The journey of the first known interstellar comet continues

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(ORDO NEWS) — Earlier this year, a comet falling into the solar system seemed to meet its end when it began to decay. But appearances can be deceiving, and a new analysis of 2I / Borisov fragmentation has shown that the main part of the comet will survive a collision with the solar system.

This is a win-win situation. The comet has partially disintegrated, which means that scientists can analyze fragments from the inside to try to understand its composition; and the epic journey of icy space rock across the galaxy will continue.

Comet 2I / Borisova was first seen in August last year. It entered the solar system with a trajectory and speed that indicated interstellar origin – making it the second known interstellar visitor and the first known interstellar comet.

She reached perihelion – the point closest to the Sun – on December 8, 2019 and continued on her way.

But in March, Polish astronomers noticed an increase in brightness, which they attributed to flashes of dust and ice, which “clearly indicate ongoing fragmentation of the nucleus.”

At the end of March, new observations from the Hubble Space Telescope confirmed this: 2I / Borisova split into at least two parts, according to a study posted on the Astronomer’s Telegram by a team led by David Jevitt from the University of California, Los Angeles.

Now, Jewitt and his team analyzed this data and found that complete decay is unlikely.

“Our observations show that the explosion and fission of the nucleus are minor events, including a small fraction of the total mass,” they wrote in a new article, which is available on the arXiv print server. “2I / Borisova will survive her passage through the planetary region to a large extent unscathed.”

Often comets from the outer solar system decay after perihelion. It is believed that the ice in the comet sublimates, which accelerates the rotation of the comet. The added torque from this process increases centripetal instability, leading to the decay of the comet.

Given that 2I / Borisova showed several similarities with comets from the outer solar system, its fragmentation was foreseen as a very likely possibility.

However, according to a new article, the outbreak in March was relatively minor. This is how it happened. From March 4 to 9, the comet significantly increased brightness – there was an outbreak on the comet.

About three weeks after the outbreak, on March 30, the secondary part of the comet was discovered. But by April 3, the second piece had disappeared; he was not visible in the observations of March 28.

According to calculations by Jevitt and his team, the explosion in early March was a cloud of about 100 square kilometers, consisting of particles about 0.1 millimeters in size. The mass of this cloud was estimated at about 20 million kilograms.

This is only a small fraction of the core, which, according to team estimates, is 300 billion kilograms, based on a radius of 500 meters, calculated from measurements of the surface of an object with high resolution.

The secondary facility, which appeared later, had a size of about 600 square meters, which corresponds to a mass of about 120,000 kg.

Astronomers keep a close eye on the comet; so far no new outbreaks have been recorded, which means that the interstellar visitor remains almost intact and has survived the stresses of perihelion.


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