Characterizing TW Hydra

TL;DR

This study uses high-resolution near-infrared spectroscopy to refine the stellar parameters of TW Hydra, revealing it as an older star with a magnetic field, providing insights into star and disk evolution.

Contribution

The paper presents a new spectral analysis of TW Hya that accurately determines its temperature, gravity, and magnetic field, updating its age and evolutionary status.

Findings

TW Hya has an effective temperature of 3800 K.

The star exhibits a magnetic field strength of 3.0 kG.

TW Hya's age is approximately 8 million years.

Abstract

At 60 pc, TW Hydra (TW Hya) is the closest example of a star with a gas-rich protoplanetary disk, though TW Hya may be relatively old (3-15 Myr). As such, TW Hya is especially appealing to test our understanding of the interplay between stellar and disk evolution. We present a high-resolution near-infrared spectrum of TW Hya obtained with the Immersion GRating INfrared Spectrometer (IGRINS) to re-evaluate the stellar parameters of TW Hya. We compare these data to synthetic spectra of magnetic stars produced by MoogStokes, and use sensitive spectral line profiles to probe the effective temperature, surface gravity, and magnetic field. A model with T_eff= 3800 K, log g=4.2, and B=3.0 kG best fits the near-infrared spectrum of TW Hya. These results correspond to a spectral type of M0.5 and an age of 8 Myr, which is well past the median life of gaseous disks.