# Estimating the chromospheric magnetic field from a revised NLTE modeling: the case of HR7428

## TL;DR

This study employs a revised NLTE semi-empirical modeling approach to estimate the magnetic field distribution in the chromosphere of HR 7428, revealing a magnetic field of approximately 500 gauss at the base.

## Contribution

It introduces a method to estimate chromospheric magnetic fields by considering non-hydrostatic equilibrium in semi-empirical models.

## Key findings

- Magnetic field at chromosphere base is about 500 gauss.
- Non-hydrostatic models suggest additional pressure components.
- The approach links magnetic pressure to model stability.

## Abstract

In this work we use the semi-empirical atmospheric modeling method to obtain the chro-mospheric temperature, pressure, density and magnetic field distribution versus height in the K2 primary component of the RS CVn binary system HR 7428. While temperature, pressure, density are the standard output of the semi-empirical modeling technique, the chromospheric magnetic field estimation versus height comes from considering the possibility of not im-posing hydrostatic equilibrium in the semi-empirical computation. The stability of the best non-hydrostatic equilibrium model, implies the presence of an additive (toward the center of the star) pressure, that decreases in strength from the base of the chromosphere toward the outer layers. Interpreting the additive pressure as magnetic pressure we estimated a magnetic field intensity of about 500 gauss at the base of the chromosphere.