Two independent studies have published in the journal Nature their unexpected findings of heavy metals in the diffuse atmosphere of comets, including that of the interstellar traveler Borisov (identified in 2019 by amateur astronomer Gennady Borisov), which is perhaps the purest comet ever. observed by mankind.
One of the teams has discovered the presence of iron and nickel in 20 comets throughout the solar system, suggesting that the presence of such elements in these icy bodies is very common. The second team of researchers has detected nickel in the atmosphere of interstellar comet 2I / Borisov . Both investigations will have important implications for the composition of planetary systems in their formative years.
“The scientific value of objects like 2I / Borisov is absolutely overwhelming, since they contain a large amount of information about their planetary systems of origin,” explains Piotr Guzik, from the Astronomical Observatory of the Jagiellonian University. “We were curious to know what atoms and molecules make up the gases around 2I / Borisov,” added Michał Drahus, from the same research center.
At the time of the observations, the comet’s mean heliocentric and geocentric distances were 2,322 AU (astronomical units) and 2,064 AU, respectively, and the mean velocity was 19.16 km / s.
A discovery that has gone unnoticed for 20 years
“A portion of the 2I / Borisov spectra shows nine emission lines that are not associated with any species that are routinely or less frequently detected on comets in the solar system. We recognized the detected lines as the spectroscopic signatures of the vapor of atomic nickel, Ni I. “, clarify the experts.
So, with data from ESO’s Very Large Telescope, the researchers also discovered that iron and nickel exist in the atmospheres of comets throughout our solar system, even those that exist far from the Sun. This is the first time. that heavy metals, generally associated with warm environments, are found in the cold atmospheres of distant comets. Quite a surprise for scientists.
Astronomers know that heavy metals exist in the dusty and rocky interiors of comets, but solid metals do not usually turn gaseous (sublimated) at low temperatures, so they are not expected to be in the atmospheres of frozen comets. Recall that comets formed about 4.6 billion years ago and have not changed since then. They are cosmic fossils to study. And to our knowledge, comets in cold space – far from the sun’s heat – should not have heavy metal atmospheres. But there they are . Nickel and iron vapor up to 300 million miles from the Sun. It is clear that we still have things to discover on the surface of these comets.
At the moment, they estimate that a comet releases about 1 gram of iron and about the same amount of nickel every second compared to about 100 kilograms of water. “Usually there is 10 times more iron than nickel, and in those comet atmospheres we find roughly the same amount for both elements. We concluded that they could come from a special type of material on the surface of the comet’s nucleus, sublimating at a fairly low temperature and releasing iron and nickel in roughly the same proportions, “commented Damien Hutsemékers, a member of the Belgian team at the University of Liège.
The researchers intend to use new telescope technology such as the Mid-Infrared ELT Imager and Spectrograph (METIS) on ESO’s upcoming Extremely Large Telescope (ELT), currently under construction in the Atacama desert region in northern Chile , to discover more about this mystery.
Referencia: Gaseous atomic nickel in the coma of interstellar comet 2I/Borisov, Nature (2021). DOI: 10.1038/s41586-021-03485-4
Iron and nickel atoms in cometary atmospheres even far from the Sun, Nature (2021). DOI: 10.1038/s41586-021-03435-0
