Fundamental properties of T dwarfs from model fits to FIRE spectra

TL;DR

This study compares atmospheric model fits to near-infrared spectra of 49 T dwarfs to derive their physical properties and assess model reliability, providing insights into substellar atmospheres and evolution.

Contribution

It offers a comparative analysis of two atmospheric models applied to T dwarf spectra, highlighting deviations and informing future model improvements.

Findings

Derived physical parameters for 49 T dwarfs including Teff and log g.

Identified discrepancies between models and observations.

Estimated radii and compared with evolutionary models.

Abstract

We fit a sample of 49 R=6000 NIR (0.9 - 2.5 micron) T dwarf spectra obtained with Magellan's FIRE spectrograph with two different atmospheric model sets to compare the derived physical parameters such as Teff, log g, cloud opacity, and rotational velocity between the models, as well as their reliability. Many of our T dwarfs have distance measurements, which allows us to calculate their radii during the fitting, which can be compared to evolutionary models to determine age, mass and potentially the presence of unseen companions. We present our spectral sample and model fits, and comment on the measured fundamental properties of these T dwarfs. Our analysis allows us to identify global deviations between models and observed spectra, and hence provides important feedback for the next generation of substellar atmospheric models.