The first interstellar comet may be the most primitive comet ever

comet 2I/Borisov It was discovered by amateur astronomer Gennady Borisov in August 2019, and a few weeks later, it was confirmed to come from outside the solar system.

He said: “2I/Borisov may represent the first true primitive comet in history.” Stefano Bagnulo, Researchers at the Armagh Observatory and Planetarium in Northern Ireland (UK), led a new study on this celestial body and published it today Nature Communications.

The author believes that the comet has never approached a star before approaching the sun in 2019.

Bagnulo and his colleagues used the instrument FORS2, Installed in a very large telescope (VLTOrganized by the European Southern Observatory (ESO) in northern Chile, the purpose is to use a Polarization, Is a measure of the angular rotation of an object under polarized light.

By studying the properties of the polarized sunlight of comet dust, researchers can gain insights into its physical and chemical properties. This technique is commonly used to study small celestial bodies in the solar system and has compared interstellar visitors with our local comets.

More primitive than Hale-Bopp

The research team found that, with the exception of Hale-Bopp, the polarization properties of 2I/Borisov are different from those of comets in the solar system. The latter attracted widespread public attention in the late 1990s because it is easy to see with the naked eye and because it is one of the most primitive comets that astronomers have ever seen.

Before the last visit, Hale-Bopp was believed to have approached the sun only once, so it was hardly affected by solar wind and radiation. This means that it is primitive, that is, its composition is very similar to that of gas and dust clouds, in which gas and dust clouds were formed about 4.5 billion years ago.

By analyzing the polarization and the color of the comet to gather clues about its composition, the research team concluded that 2I/Borisov is actually more primitive than Hale-Bopp. This means that it contains unchanging traces of the formation of gas and dust clouds.

“The fact that the two comets are so similar shows that the environment where 2I/Borisov originated is not very different in composition from the environment of the early solar system,” he said. Alberto Cellino, Is a co-author of researchers and researchers from the Italian National Institute of Astrophysics (INAF) Turin Astrophysical Observatory.

“Another interesting result is that it was confirmed that 2I/Borisov is bluer than Hale-Bopp, indicating that the particles ejected by interstellar comets may be smaller,” another author pointed out Tony Santana Rose, From the American Institute of Space Science University of Barcelona And University of Alicante, He has taken a photometric measurement of the original object.

He emphasized: “As the first interstellar comet ever observed, 2I/Borisov is a unique celestial body.” We don’t know how often these objects pass through the solar system, so maybe we are facing a golden opportunity to observe To such an object. Because of this, it is very important to analyze all the observations of the institution, which prompts us to study its composition in detail, and most importantly, to determine the spatial erosion that it has suffered throughout its history. “

For Bagnullo, he hopes that the astronomy community will have another opportunity to study wandering comets in detail before the end of the decade. “ESA plans to launch a Kite Interceptor He said that by 2029, if another visiting interstellar object can be found in a suitable orbit, it will have the ability to reach another visiting interstellar object.

Although 2I/Borisov was the first wandering comet to pass the sun, it was not the first interstellar visitor. In 2017, Oumuamua was observed to pass through our solar system for the first time. Originally classified as a comet, Oumuamua was later reclassified as an asteroid due to lack of coma.