X-Shooter observations of low-mass stars in the Eta Chamaeleontis association

TL;DR

This study uses VLT/X-Shooter spectra to measure stellar and accretion properties of low-mass stars in Eta Chamaeleontis, revealing ongoing accretion and comparing accretion rates with previous methods and other regions.

Contribution

First comprehensive spectroscopic analysis of low-mass stars in Eta Chamaeleontis using broad wavelength coverage to measure accretion properties.

Findings

Five of eight stars with IR excess show UV excess indicating accretion.

Accretion rates are consistent with other young star-forming regions.

Measured accretion rates tend to be higher than previous H-alpha based estimates.

Abstract

The nearby Eta Chamaeleontis association is a collection of 4-10 Myr old stars with a disk fraction of 35-45%. In this study, the broad wavelength coverage of VLT/X-Shooter is used to measure the stellar and mass accretion properties of 15 low mass stars in the Eta Chamaeleontis association. For each star, the observed spectrum is fitted with a non-accreting stellar template and an accretion spectrum obtained from assuming a plane-parallel hydrogen slab. Five of the eight stars with an IR disk excess show excess UV emission, indicating ongoing accretion. The accretion rates measured here are similar to those obtained from previous measurements of excess UV emission, but tend to be higher than past measurements from H-alpha modeling. The mass accretion rates are consistent with those of other young star forming regions.