After two decades of discussion, scientists are coming closer to determining the precise composition of the sun and, by extension, the cosmos. The sun is comprised mostly of hydrogen and helium. Additionally, there are heavier components like as oxygen and carbon, although the exact amount is contested. Researchers reveal that new discoveries of ghostly subatomic particles known as neutrinos indicate that the sun has an abundant supply of “metals,” the name astronomers use for all atoms heavier than hydrogen and helium.
Livia Ludhova, a physicist at Germany’s Jülich Research Center, explains that the findings “are entirely consistent with a high metallicity” for the sun. Elements heavier than hydrogen and helium are essential for the formation of rocky-iron planets such as Earth and the sustenance of life forms such as humans. Oxygen is by far the most prevalent element in the universe, followed by carbon, neon, and nitrogen.
However, scientists do not know the precise proportion of these atoms to hydrogen, the most abundant element in the universe. Because astronomers often use the sun as a reference to determine elements abundances in distant stars and galaxies, and two methodologies predict vastly different chemical compositions for our star, this is the case.
An approach that uses the sun’s internal vibrations to determine its interior structure prefers a high metal content. The second technique determines the sun’s make-up by studying the way its surface atoms absorb different colors of light. Using the alternate technique, researchers discovered that the solar abundances of oxygen, carbon, neon, and nitrogen were 26–42% lower than previous estimates.
Utilizing solar neutrinos is a new technology that might settle the long-standing dispute. These particles are produced by nuclear events in the center of the sun that convert hydrogen to helium. About 1 percent of the sun’s energy comes from carbon, nitrogen, and oxygen processes that turn hydrogen into helium without using any energy. The more carbon, nitrogen, and oxygen the sun truly contains, the more neutrinos should be emitted by the CNO cycle.
There was a report of the detection of CNO neutrinos by the Borexino subterranean detector in Italy in 2020 (SN: 6/24/20). Ludhova and her team have now caught adequate neutrinos to determine that carbon and nitrogen atoms are 0.06 percent as common as hydrogen atoms in the sun. Neutrinos have never before been employed to determine the sun’s elemental make-up until now.
And despite the fact that this figure seems little, it is much more than the one advocated by astronomers who support a sun with a high metal content. And its 70 percent higher than what a sun with little metal content should have.
Marc Pinsonneault, an astronomer at Ohio State University in Columbus who has long campaigned for a high-metal sun, describes the discovery as “excellent.” They have shown conclusively that the present low-metallicity answer contradicts the evidence.
Ludhova explains that because to uncertainty in both the measured and expected neutrino quantities, Borexino cannot completely rule out a low-metal sun.
According to Gal Buldgen, an astronomer at Geneva University in Switzerland who advocates a low-metal sun, the latest research represents “a big advance.” However, the expected quantity of CNO neutrinos is based on very simplistic solar models, which he critiques. According to Buldgen, these models fail to account for the sun’s spin, which might result in the mixing of chemical elements throughout the course of its lifetime and alter the quantity of carbon, nitrogen, and oxygen in the sun’s core, hence altering the expected number of CNO neutrinos.
Ludhova states that further neutrino observations are required for a definitive conclusion. Borexino will close in 2021, but other attempts may be able to fill the hole. The stakes are elevated. Pinsonneault said, “We’re debating what the universe is comprised of since the sun is the standard for all of our research.”
If the sun contains far more carbon, nitrogen, and oxygen than previously believed, then so does the whole cosmos. “This alters our conception of how chemical components are formed. It alters our knowledge of how stars develop and die, according to Pinsonneault. And, he says, it serves as a reminder that even the most-studied star, our sun, has mysteries.