Evolution of solar and stellar coronal abundances due to magnetic activity

TL;DR

This work investigates how coronal element abundances evolve with magnetic activity across three timescales: active-region lifetimes, the solar cycle, and stellar evolution. It centers on the First Ionization Potential (FIP) effect and its inverse (iFIP), with the ponderomotive force as a key mechanism linking Alfvén-wave dynamics to fractionation and thus to observed coronal compositions. By examining AR evolution (Emergence–Stable–Dissipation phases) and solar-cycle trends, the authors show that coronal abundances reflect a progression from photospheric-like to coronal composition, modulated by heating regimes and external reconnection, culminating in a broader solar–stellar connection. The study extends these insights to other stars, noting iFIP is common in young, active systems while older stars tend toward solar-like FIP, while also outlining observational and modeling challenges that remain to be overcome.

Abstract

We discuss the evolution of solar coronal element abundances over an active region lifetime. Magneto-convection drives the complexity of magnetic fields that emerge above the photosphere. This complexity is dissipated, together with that of the overlying pre-existing fields, through dynamic events such as flares. A period of stable "ordinary" coronal heating ensues, before the concentrated fields are dissipated through interactions with the surrounding environment. The evolution of coronal abundances can be explained by the First Ionisation Potential (FIP) effect operating within this framework. We extend the discussion from magnetic activity on timescales of active region lifetimes (months), to the solar cycle (years), and stellar evolution (eons). The broad picture shows intriguing similarities that may prompt new investigations.

Figures (3)

• Figure 1: SDO/AIA 171 Å images of the evolution of AR 11158/11171 as it passes the central meridian on three rotations. The magnetically complex, dynamic, and compact structure of emerging AR 11158 develops into the larger, diffuse, non-flaring AR 11171, and finally devolves into a filament channel before dissipation in the quiet Sun.
• Figure 2: Temporal evolution of the full disk integrated F10.7 cm radio flux (blue) and the FIP bias (red) between April 2010 and May 2014. The data are 27-day Carrington rotation running averages. The FIP bias is measured by computing the full disk temperature distribution (DEM) using spectral lines of the low FIP elements (Mg, Si, Fe) observed by SDO/EVE and modelling the intensity of a strong line from the high FIP element Ne. The ratio of predicted to observed intensity yields the FIP bias. This plot is an adaption of Figure 2 from Brooks et al. (2017) Brooks2017 and their error estimate is plotted as the red vertical bar.
• Figure 3: FIP bias against stellar age for a sample of magnetically active stars Seli2022. We plot a subset of the original literature sample excluding evolved RS CVn-type stars, those with undetermined ages, and Proxima Centauri. The definitions of the stellar type in the legend are taken from Table 1 in the original paper. The ages and FIP bias values are taken from Table 2. We use the "literature" FIP bias values, which are derived from measurements of the coronal to photospheric ratio of the mean abundances of some combination of C, N, O, and Ne relative to Fe i.e. [X/Fe] = $\log$[X/Fe]$_{cor}$-$\log$[X/Fe]$_{phot}$. This definition means values of [-0.5,0,0.5] correspond to a solar FIP bias of [0.32,1,3.2]. The active Sun appears at 4.57 Gyr. Stellar measurements of photospheric abundances were used when available, but otherwise solar photospheric abundances from Asplund2009 and Drake2005 for Ne were used. The specific values are given in Table A.1 of the Appendix of the paper Seli2022.