Ordinary Stars as Potential TeV Cosmic-Ray Accelerators

TL;DR

This paper explores how ordinary stars like the Sun could serve as nearby sources of TeV cosmic rays through shock-drift acceleration in their chromospheres, potentially explaining local cosmic-ray features.

Contribution

It demonstrates that quiescent stars can accelerate particles to TeV energies via shock-drift processes, providing a new perspective on local cosmic-ray sources.

Findings

Stars can accelerate particles to TeV energies through chromospheric shock-drift acceleration.

Stellar environments may contribute to the observed TeV cosmic-ray spectrum features.

Stars could explain the local excess of TeV electrons and positrons.

Abstract

Recent observations of cosmic rays increasingly point to the existence of nearby sources - so-called "local tevatrons", capable of accelerating particles to TeV energies. In this study, we examine the potential of a typical main-sequence star, represented by the Sun, to act as a source of TeV cosmic rays (CRs). We focus on identifying plausible mechanisms through which a quiescent star can accelerate charged particles to relativistic energies. We show that shock-drift acceleration processes operating within the chromospheres of the Sun and similar stars can accelerate particles to energies reaching the TeV scale. Additionally, we provide quantitative estimates of both the maximum achievable particle energies, spectral index of energy spectrum and the resulting cosmic-ray fluxes that such stellar environments could realistically produce. Our results indicate that ordinary stars could potentially contribute to the fine structure observed in the cosmic-ray spectrum at TeV energies and may help explain the local excess of TeV-scale electrons and positrons detected by H.E.S.S. and other observatories.