Rare interstellar comet 2I/Borisov could be carrying water from another star system, say scientists tracking eerie cosmic traveller

This is the first time scientists have seen water from another planetary system


                            Rare interstellar comet 2I/Borisov could be carrying water from another star system, say scientists tracking eerie cosmic traveller

The interstellar comet 2I/Borisov, which is currently speeding through our solar system, could be carrying water from another star system, according to astronomers. This is the first time scientists have detected water in our solar system that has come from another planetary system. 

The discovery was reported by a team — led by Adam J. McKay from the NASA Goddard Space Flight Center — in a pre-print version on arXiv.org, which is an e-print service operated by Cornell University.

“This provides the first measurement of the water production rate in this very intriguing object,” says the research team in their observations.

The team, which also includes scientists from McDonald Observatory, the University of Texas at Austin, and Johns Hopkins Applied Physics Laboratory, says, “More detailed characterization of 2I/Borisov, including compositional information and properties of the nucleus, are needed to fully interpret the observed H2O (water) production rate.”

The observations were made on October 11, 2019, using the ARCES instrument mounted on the 3.5-meter Astrophysical Research Consortium (ARC) Telescope at Apache Point Observatory in Sunspot, New Mexico. 

“We estimate an H2O (water) active area of 1.7 square km, which for current estimates for the size of 2I/Borisov suggests active fractions between 1-150%, consistent with values measured in solar system comets,” says the pre-print version of the study. The complete findings will be submitted to The Astrophysical Journal Letters. 

Scientists have previously stated that research work on 2I/Borisov, which is from another star, will be "transformative for planetary astronomy" and the current discovery raises questions if there are planetary systems similar to ours. 

The comet 2I/Borisov, as seen on October 12 with NASA’s Hubble Space Telescope. Scientists believe the comet is from another solar system. (NASA, ESA and David Jewitt/UCLA)

The comet is following a path around the sun at a speed of approximately 110,000 miles per hour, or about as fast as the Earth travels around the sun.

“Comets have a primitive volatile composition that is thought to reflect the conditions present in their formation region in the protosolar disk. This makes studies of cometary volatiles powerful for understanding the physical and chemical processes occurring during planet formation. The discovery of interstellar comet 2I/Borisov provides an opportunity to sample the volatile composition of a comet that is unambiguously from outside our own solar system, providing constraints on the physics and chemistry of other protostellar disks,” say the researchers in their findings.

Initially dubbed as C/2019 Q4 (Borisov), the object was first detected on August 30 by Gennady Borisov, an amateur astronomer at the MARGO observatory in Nauchnij, Crimea. The first interstellar object to pass through the solar system — 'Oumuamua — was detected and confirmed in October 2017. Soon after its discovery, NASA had said the comet was 260 million miles or 420 million kilometers from the sun and is expected to reach its closest point, or perihelion, on December 8, 2019, at a distance of about 190 million miles. 

According to a previous observation, 2I/Borisov has a dust-dominated morphology, a reddish hue, and its solid nucleus is about 1 km in radius. The estimated nucleus size of 2I/Borisov, says scientists, is common among the solar system's comets. Based on its initial characteristics, scientists have noted that the comet is exactly what astronomers had expected. 

In the current study, researchers think that 2I/Borisov is releasing water vapor. Comets in our solar system are well known for being rich in water. Accordingly, say scientists, the finding is exciting as it reiterates previous observations that Borisov resembles comets from our solar system. 

“On 11 October, they spotted a telltale signature of oxygen in the spectra of light coming from the comet. Although comets can produce oxygen in a couple of different ways, researchers say that the most likely explanation is water breaking apart into hydrogen and oxygen,” describes an article published in Nature. 

“The scientists compared the amount of water in the comet to the amount of cyanide it contains, which other researchers had previously spotted. The ratio of water to cyanide is consistent with that seen in comets from the Solar System. That reinforces scientists’ growing idea that Borisov is not all that different from most comets, despite coming from a different star system,” says the report published in Nature.

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