Effects of Nearby Galactic Supernovae on the Composition of Solar System Atmospheres

Abstract

Pluto’s surface and atmosphere compositions were almost completely unknown until 2015 when the New Horizons spacecraft did a Pluto flyby which revealed that much of Pluto’s surface is covered in dark tholins (complex carbons) giving it a reddish hue. It is theorized that radiation hitting methane (CH4) and nitrogen gas (N2) molecules in Pluto’s atmosphere would initiate a sequence of reactions leaving tholins on the surface. However, the source of that radiation is uncertain, and it has been shown that solar radiation does not solely explain the phenomenon. We hypothesized that a past near-Earth supernova (SN) could be the source of said radiation. In this research, we have carried out a literature review and compiled a list of past supernovae and their known and inferred characteristics. Then, we researched their estimated energy outputs and computed their respective energy fluxes in our Solar System. These calculations allow us to examine how these historical supernovae would affect a solar system with an arbitrary atmosphere in terms of the rate and amount of destroyed atmospheric molecules. Our findings suggest that radiation from a past SN is a plausible explanation for the dark tholins present on Pluto’s surface.