A new Generation of Standard Solar Models

TL;DR

This paper introduces a new generation of standard solar models incorporating recent nuclear reaction rates, improved equation of state, and a novel opacity uncertainty treatment, comparing high- and low-metallicity models against solar observations.

Contribution

It presents a comprehensive set of updated solar models with advanced physics and a novel opacity uncertainty framework, analyzing their agreement with various solar observables.

Findings

High-Z models fit solar data well but have issues below the convective zone.

Low-Z models show significant disagreement with solar data.

Opacity parametrizations alone cannot fully resolve the solar abundance problem.

Abstract

We compute a new generation of standard solar models (SSMs) that includes recent updates on some important nuclear reaction rates and a more consistent treatment of the equation of state. Models also include a novel and flexible treatment of opacity uncertainties based on opacity kernels, required in the light of recent theoretical and experimental works on radiative opacity. Two large sets of SSMs, each based on a different canonical set of solar abundances with high and low metallicity (Z), are computed to determine model uncertainties and correlations among different observables. We present detailed comparisons of high- and low-Z models against different ensembles of solar observables including solar neutrinos, surface helium abundance, depth of convective envelope and sound speed profile. A global comparison, including all observables, yields a p-value of 2.7$\sigma$ for the high-Z model and 4.7$\sigma$ for the low-Z one. When the sound-speed differences in the narrow region of $0.65 < r/R_{sun} < 0.70$ are excluded from the analysis, results are 0.9$\sigma$ and 3.0$\sigma$ for high- and low-Z models respectively. These results show that: high-Z models agree well with solar data but have a systematic problem right below the bottom of the convective envelope linked to steepness of molecular weight and temperature gradients, and that low-Z models lead to a much more general disagreement with solar data. We also show that, while simple parametrizations of opacity uncertainties can strongly alleviate the solar abundance problem, they are insufficient to substantially improve the agreement of SSMs with helioseismic data beyond that obtained for high-Z models due to the intrinsic correlations of theoretical predictions. All the detailed information of the new solar models, can be found online: http://www.ice.cat/personal/aldos/Solar_Data.html