Revisiting the space weather environment of Proxima Centauri b by Cecilia Garraffo et al. on Wednesday 30 November

Close-in planets orbiting around low-mass stars are exposed to intense

energetic photon and particle radiation and harsh space weather. We have

modeled such conditions for Proxima Centauri b (Garraffo et al. 2016b), a rocky

planet orbiting in the habitable-zone of our closest neighboring star, finding

a stellar wind pressure three orders of magnitude higher than the solar wind

pressure on Earth. At that time, no Zeeman-Doppler observations of the surface

magnetic field distribution of Proxima Cen were available and a proxy from a

star with similar Rossby number to Proxima was used to drive the MHD model.

Recently, the first ZDI observation of Proxima Cen became available (Klein et

al. 2021). We have modeled Proxima b's space weather using this map and

compared it with the results from the proxy magnetogram. We also computed

models for a high-resolution synthetic magnetogram for Proxima b generated by a

state-of-the-art dynamo model. The resulting space weather conditions for these

three scenarios are similar with only small differences found between the

models based on the ZDI observed magnetogram and the proxy. We conclude that

our proxy magnetogram prescription based on Rossby number is valid, and

provides a simple way to estimate stellar magnetic flux distributions when no

direct observations are available. Comparison with models based on the

synthetic magnetogram show that the exact magnetogram details are not important

for predicting global space weather conditions of planets, reinforcing earlier

conclusions that the large-scale (low-order) field dominates, and that the

small-scale field does not have much influence on the ambient stellar wind.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.15697v1