In October 2019 astronomers first observed the comet which was later renamed ‘2I / Borisov’. A somewhat special comet for being the first known to come from another single systemr, for being an interstellar comet. But as more has been studied, more interesting details about it have been discovered, such as its composition or, now, its unaltered form.
In a new study published in Nature, researchers have taken a closer look at the comet to understand its origin and history. Turns out that it is the most pristine astronomical object discovered to date.
Without approaching any sun
Comets are essentially old bits of material discarded from the planet-forming phase of solar systems. Those that come from our own solar system are of great interest to astronomers as they allow better understand the early stages of formation of the Solar System. If they come from another solar system? More interest arouse still.
The problem with comets is that with the passage of time they degrade, a lot. Over time the solar wind and radiation consume the comet, causing it to change its composition, shape and characteristics. The main cause? The stars and what they emit when to all nearby celestial bodies such as comets.
But the case of 2I / Borisov seems to be different. Besides being the second interstellar object discovered after Oumuamua, It also seems to be the one that has been least altered. That is, according to the new study, this space object may represent the most pristine comet ever discovered. In turn, this may indicate that it has never passed near a stellar body before our Sun.
The study authors analyzed 2I / Borisov polarimetry to measure the polarization of sunlight as it passed through the comet’s dusty tail. 2I / Borisov was found to be photometrically distinct from the vast majority of comets in our Solar System, with much higher levels of light polarization.
Previously, in fact, only one other comet has been discovered that comes close to such levels of polarization, Comet Hale-Bopp. Hale-Bopp passed near us in 1997 and because of how little altered it was, it is believed that it had never passed near the Sun before in its history, hence it had hardly any alterations. But the case of 2I / Borisov is even more interesting, which could mean you’ve never been near a star before, not even the one where it was formed.
Via | NewScientist
More information | Nature and ESO