An Earth-like stellar wind environment for Proxima Centauri c

TL;DR

This study models the stellar wind environment of Proxima Centauri c using numerical simulations to understand its impact on the planet's atmosphere and magnetic interactions, crucial for future atmospheric characterization.

Contribution

It provides the first physically-realistic simulations of Proxima Centauri's stellar wind environment around Proxima c, including magnetic cycle effects and implications for atmospheric stability.

Findings

Stellar wind pressures similar to Earth's, with slight increases during star activity peaks.

Weak magnetic fields result in minimal Joule heating of the planet's atmosphere.

Assessment of extreme conditions for the nearby Proxima d exoplanet candidate.

Abstract

A new planet has been recently discovered around Proxima Centauri. With an orbital separation of $\sim$$1.44$ au and a minimum mass of about $7$ $M_{\oplus}$, Proxima c is a prime direct imaging target for atmospheric characterization. The latter can only be performed with a good understanding of the space environment of the planet, as multiple processes can have profound effects on the atmospheric structure and evolution. Here, we take one step in this direction by generating physically-realistic numerical simulations of Proxima's stellar wind, coupled to a magnetosphere and ionosphere model around Proxima c. We evaluate their expected variation due to the magnetic cycle of the host star, as well as for plausible inclination angles for the exoplanet orbit. Our results indicate stellar wind dynamic pressures comparable to present-day Earth, with a slight increase (by a factor of 2) during high activity periods of the star. A relatively weak interplanetary magnetic field at the distance of Proxima c leads to negligible stellar wind Joule heating of the upper atmosphere (about $10\%$ of the solar wind contribution on Earth) for an Earth-like planetary magnetic field ($0.3$ G). Finally, we provide an assessment of the likely extreme conditions experienced by the exoplanet candidate Proxima d, tentatively located at $0.029$ au with a minimum mass of $0.29$ $M_{\oplus}$.