Temperature and density profiles in the corona of main-sequence stars induced by stochastic heating in the chromosphere

TL;DR

This paper extends a plasma heating model to main-sequence stars, demonstrating that stochastic chromospheric heating can produce solar-like coronae across various stellar masses, with limitations for the most massive stars.

Contribution

It applies a new coronal heating model to main-sequence stars, predicting solar-like coronae and analyzing the influence of stellar mass on coronal profiles.

Findings

Predicts hot, rarefied coronae in main-sequence stars of various masses.

Model is not applicable to the most massive stars lacking convective layers.

Stellar mass influences the shape of temperature and density profiles.

Abstract

All but the most massive main-sequence stars are expected to have a rarefied and hot (million-Kelvin) corona like the Sun. How such a hot corona is formed and supported has not been completely understood yet, even in the case of the Sun. Recently, Barbieri et al. (A&A 2024, J. Plasma Phys. 2024) introduced a new model of a confined plasma atmosphere and applied it to the solar case, showing that rapid, intense, intermittent and short-lived heating events in the high chromosphere can drive the coronal plasma into a stationary state with temperature and density profiles similar to those observed in the solar atmosphere. In this paper we apply the model to main-sequence stars, showing that it predicts the presence of a solar-like hot and rarefied corona for all such stars, regardless of their mass. However, the model is not applicable as such to the most massive main-sequence stars, because the latter lack the convective layer generating the magnetic field loop structures supporting a stationary corona, whose existence is assumed by the model. We also discuss the role of stellar mass in determining the shape of the temperature and density profiles.