An international team of astronomers has become the first research team to identify carbon isotopes in the atmosphere of a gas giant
![An illustration of the "birth" environments of a star in the preplanetary disk forming around a "young" star. The two stars to the left of the carbon monoxide snowline are Jupiter and Neptune, while the extrasolar planet to the right of the snowline formed well beyond this line. [Courtesy: Yapeng Zhang]](https://www.hayadan.org.il/images/content3/2021/08/Birth-Environments-of-Planets-in-Proto-Planetary-Disk-1536x8691-1.jpg.webp)
[Translation by Dr. Moshe Nachmani]
The team was able to identify different configurations of carbon (isotopes) in the giant gas star three hundred light-years away from Earth (TYC 8998-760-1 b). The faint signal was measured by the European Southern Observatory's (ESO) Very Large Telescope (VLT) in Chile and suggests that the star may be relatively rich in the isotope carbon-13. The astronomers speculate that this result originates from the fact that the star was formed at a great distance from its parent star. The study was published in the scientific journal Nature.
Isotopes are different forms of the same element but with a different number of neutrons in the atomic nucleus. For example, a normal carbon atom usually has six neutrons (carbon-12), but sometimes it includes seven neutrons (carbon-13) or eight (carbon-14). This result does not significantly change the properties of the carbon atom. And yet, different isotopes of the same element react slightly differently under the same conditions. Isotopes, therefore, provide advantages in a variety of applications in a wide range of research fields: from the diagnosis of heart disease and cancer, to measurements of climate change and ending with the determination of the age of fossils and rocks.
The international team of researchers discovered an unusual ratio between the types of isotopes in the atmosphere of the young giant star. Carbon is usually found in the form of the gaseous substance carbon monoxide (CO). The star has fourteen times the mass of the planet Jupiter and twice the size of Jupiter. Hence, astronomers classify it as a super-Jupiter. The team of scientists was able to differentiate between the signals of carbon-13 and carbon-12, this in light of the fact that these two isotopes absorb radiation at slightly different wavelengths (colors). "It's really quite special that we can measure this difference between the isotopes in the atmosphere of an extrasolar planet at such a great distance," said the lead researcher. The astronomers predicted that they would detect one carbon-13 atom out of 70 carbon atoms, but the actual concentration appears to be at least twice that. It is hypothesized that the higher concentration of carbon-13 is somehow related to the way the star formed. The main researcher explains: "The star is 150 times farther away from its parent star relative to the distance of Earth's orbit from the sun. At such a great distance, the resulting ice may have contained larger amounts of carbon-13, a fact that led to a greater concentration of this isotope in the star's atmosphere today." The assumption is that the enrichment in carbon-13 is related to the stagnation of carbon monoxide in the preplanetary disks from which the star was formed. In that case, it means that planets in the solar system have not accumulated enough carbon-13-rich ice. The reason may lie in the fact that in the solar system, the distance from which carbon monoxide begins to freeze is beyond the orbit of the planet Neptune. Therefore, it is likely that carbon monoxide in its icy state was hardly incorporated into the stars of the solar system, which would have led to a higher isotope ratio.
The extrasolar planet TYC 8998-760-1 b was discovered just two years ago by PhD student Alexander Bohn, who is one of the authors of the paper. He adds and says: "It's wonderful that this discovery happened close to "my" star. This discovery will probably be the first of many others. It is expected that in the future measurements of the isotope ratio will help us understand exactly how, where and when stars were formed. This initial finding is just the beginning of this fascinating field."
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How did ice 'cause' the formation of carbon-13? A puzzling theory, but on the subjects of distant stars and galaxies you can write any theory you want. No one will disagree with you…