Large-scale magnetic fields and anomalies of chemical composition of stellar coronae

Abstract

We present evidence that anomalies in abundance of the chemical admixtures with the low first ionization potential (FIP) in the low corona of the late-type stars can be related to a topology of the large-scale magnetic field. Observational data from Ulysses and the Stanford Solar Observatory reveal the high correlations between the FIP effect of the solar wind and amount of the open magnetic flux. To analyze the stellar activity data we relate the amount of the open magnetic flux with the ratio between poloidal and toroidal magnetic field of a star. The solar-type stars show the increase abundance of the low FIP elements relative to elements with the high FIP with the decrease of the large-scale poloidal magnetic field (and increase the toroidal component of the magnetic field). The branch of the fully convective stars demonstrates inversion of the FIP-effect. This inversion can result from strong coronal activity, which is followed by the strong poloidal magnetic on these stars.

Coronal Elemental Abundance: New Results from Soft X-Ray Spectroscopy of the Sun

“…Over solar cycle time scales, Brooks et al (2017) showed a strong correlation of Ne coronal to photospheric abundance ratios, to the phases of the solar cycle. Pipin and Tomozov (2018) further extended this to stars and have shown that the FIP bias variations are likely related to the large scale coronal magnetic field and activity level of the toroidal magnetic field. Such variations could also occur at shorter time scales and smaller spatial scales.…”