The impact of M-dwarf atmosphere modelling on planet detection

TL;DR

This study compares different stellar atmosphere models for M-dwarfs to understand their impact on star characterization and exoplanet detection, highlighting discrepancies that influence the interpretation of observational data.

Contribution

It provides a detailed comparison of ATLAS9, MARCS, and Drift-Phoenix models in the M-dwarf parameter space, emphasizing differences affecting stellar and exoplanet parameter estimation.

Findings

Discrepancies found between ATLAS and MARCS models in hotter stellar regions.

MARCS and Drift-Phoenix models show good agreement with less than 300K variance.

Synthetic photometric fluxes differ among models, especially in the optical range.

Abstract

Being able to accurately estimate stellar parameters based on spectral observations is important not only for understanding the stars themselves but it is also vital for the determination of exoplanet parameters. M dwarfs are discussed as targets for planet detection as these stars are less massive, less luminous and have smaller radii making it possible to detect smaller and lighter planets. Therefore M-dwarfs could prove to be a valuable source for examining the lower mass end of planet distribution, but in order to do that, one must first take care to understand the characteristics of the host stars well enough. Up to date, there are several families of stellar model atmospheres. We focus on the ATLAS9, MARCS and Drift-Phoenix families in the M-dwarf parameter space. We examine the differences in the (Tgas, pgas) structures, synthetic photometric fluxes and related colour indices.We find discrepancies in the hotter regions of the stellar atmosphere between the ATLAS and MARCS models. The MARCS and Drift-Phoenix models appear to agree to a better extend with variances of less than 300K. We have compiled the broad-band synthetic photometric fluxes of all models for the Johnson UBVRI and 2MASS JHKs. The fluxes of MARCS differ from both ATLAS and Drift-Phoenix models in the optical range.