Modelling the TESS light curve of Ap Si star MX TrA

TL;DR

This paper models the TESS light curve of the Ap Si star MX TrA by integrating surface chemical distributions with synthetic stellar atmosphere models, achieving high-precision fits and analyzing the effects of element stratification on variability.

Contribution

It introduces a detailed modeling approach combining Doppler Imaging surface maps with synthetic flux calculations to accurately reproduce observed light curves of Ap stars.

Findings

Synthetic light curve fits observational data with <0.001 mag accuracy.

Element stratification influences variability amplitude and phase.

Wavelength-dependent amplitude and phase behaviors are consistent with Ap Si star characteristics.

Abstract

The TESS light curve of the silicon Ap star MX TrA was modelled using the observational surface distribution of silicon, iron, helium, and chromium obtained previously with the Doppler Imaging technique. The theoretical light curve was calculated using a grid of synthetic fluxes from line-by-line stellar atmosphere models with individual chemical abundances. The observational TESS light curve was fitted by synthetic one with an accuracy better than 0.001~mag. The influence of Si and Fe abundance stratification on the amplitude of variability was estimated. Also the wavelength dependence of the photometric amplitude and phase of the maximum light was modelled showing the typical for Ap Si stars behaviour with increased amplitude and anti-phase variability in far ultraviolet caused by the flux redistribution.