The Two-component Model of the 'spokes' in Saturn's Rings

Abstract

The spokes observed in Saturn's rings have been a subject of scientific debate since their discovery by Stephen J. O'Meara in the 1970s and their confirmation by the Voyager flybys in the early 1980s (Smith et al., 1982). While the Cassini spacecraft confirmed that the spokes are linked to Saturn's magnetosphere, their exact formation mechanism remains uncertain. This paper proposes that the spokes in Saturn's rings consist of two distinct components: (1) carbonaceous materials, namely pyrolytic carbon with diamagnetic properties and potentially other various forms of carbon-bearing compounds, which persist over longer timescales, and (2) rapidly forming and dissipating diamagnetic ice grains, which interact with Saturn's magnetosphere on much shorter timescales. We suggest that the spokes consist of diamagnetic pyrolytic carbon that has coated silicates through the process of high-temperature Chemical Vapour Deposition (CVD) during the formation of Saturn's circumplanetary disk. Additionally, the spokes consist of diamagnetic ice particles that can disappear within minutes to hours due to sublimation. The photoelectric effect causes the pyrolytic carbon grains to lose electrons, thus becoming paramagnetic, which results in their attraction back to the main B ring structure. We suggest that Saturn's rings are charged by the solar wind, generating a magnetic field that emanates orthogonally above and below the B ring plane due to the movement of charged particles in the rings. Statistical analysis of Cassini data reveals significant correlations between spoke activity and both Saturn's magnetospheric rotation and solar elevation angle, providing strong support for an electromagnetic mechanism in spoke formation. This hypothesis suggests that the visibility of the spokes is dictated by illumination conditions and electromagnetic effects.