The Effective temperature scale of M dwarfs from spectral synthesis

TL;DR

This study compares observed low-resolution spectra of 60 M dwarfs with PHOENIX BT-Settl models to derive effective temperatures and improve stellar atmosphere models.

Contribution

It provides a new effective temperature scale for M dwarfs based on spectral synthesis and compares it with existing relations, enhancing model accuracy.

Findings

Derived effective temperature-spectral type relations.

Identified discrepancies between models and observations.

Suggested improvements for stellar atmosphere opacities.

Abstract

We present a comparison of low-resolution spectra of 60 stars covering the whole M-dwarf sequence. Using the most recent PHOENIX BT-Settl stellar model atmospheres (see paper by F. Allard, in this book) we do a first quantitative compari- son to our observed spectra in the wavelength range 550-950 nm. We perform a first confrontation between models and observations and we assign an effective tempera- tures to the observed M-dwarfs. Teff-spectral type relations are then compared with the published ones. This comparison also aims at improving the models' opacities.