Sun’s Silver Content Exceeds Earlier Estimates, Study Finds

Researchers at Uppsala University report that the Sun contains about 55% more silver than earlier estimates suggested. Using updated, more physically realistic models of the Sun’s atmosphere, the team has revised the solar abundance of this trace element—an adjustment that helps close a long-standing discrepancy between the Sun and primitive solar-system material.

Although the Sun is dominated by hydrogen and helium, heavier elements such as silver, iron, and carbon exist in tiny fractions. Those fractions matter because they preserve information about how matter formed and evolved throughout the cosmos. In particular, the elemental composition of the Sun serves as a baseline for understanding other stars and the chemical development of the Milky Way.

The new result comes from spectroscopic analysis: when atoms in the Sun’s outer layers absorb specific wavelengths of light, they create dark absorption lines—fingerprints tied to individual elements. By comparing these silver spectral lines to theoretical predictions, the researchers infer how much silver must be present to reproduce the observed absorption features.

Earlier solar models relied on simplified assumptions about the Sun’s atmosphere and the behavior of silver atoms. In the new work, the team built a more detailed framework by combining a dynamical description of the Sun’s upper layers with improved atomic-physics calculations. Crucially, the calculations incorporate non-equilibrium (non-LTE) effects, allowing the radiation field to influence the same silver atoms responsible for the absorption lines.

This refinement changed the interpretation of the measured spectral signatures. With the enhanced model, the researchers could match the spectral lines more accurately, leading to the higher inferred silver content. The update also resolves a “missing silver” problem: previously, the solar silver abundance was lower than the amount found in chemically primitive meteorites formed around 4.6 billion years ago.

Now, the Sun’s revised silver abundance aligns much better with these ancient meteorites. That agreement strengthens the connection between stellar spectroscopic measurements and the composition of early solar-system building blocks.

The approach is also poised to become a broader tool. The team plans to apply the same non-LTE modeling strategy to other stars, aiming to track where silver forms and how it becomes distributed across the Milky Way over cosmic time.

The calculations were performed using the Swedish supercomputer Tetralith at the National Supercomputer Centre at Linköping University, bringing together expertise in stellar physics and atomic modeling to produce a more reliable abundance determination.

Keywords

solar silver, spectroscopy, non-LTE, stellar atmospheres, non-equilibrium modeling, chemical evolution, atomic physics, silver abundance, meteorites, Milky Way