S and VV Corona Australis: Spectroscopic Variability in Two Young Binary Star Systems

TL;DR

This study uses multi-epoch high-resolution near-infrared spectroscopy to analyze the spectral variability and evolutionary stages of two young binary T Tauri star systems, S CrA and VV CrA, revealing their high accretion activity and transitional status.

Contribution

It provides the first spectral types for all stars in these systems and compares their properties, highlighting their transitional evolutionary stage between Class I and II.

Findings

Stars have similar spectral types (K7-M1).

Both systems show high accretion luminosities.

Emission lines are variable over time.

Abstract

We used high-resolution near-infrared spectroscopy from the NIRSPEC instrument on the Keck II telescope, taken over multiple epochs spanning five years, to examine two young binary T Tauri star systems, S Corona Australis and VV Corona Australis. The stars in these 1-2" separation systems have optically thick circumstellar disks and high extinctions at optical and near-infrared wavelengths. Using a combination of new and archival data, we have determined the spectral types of all the stars in these two systems for the first time, examined the variable NIR veiling, measured the emission line equivalent widths, and created spectral energy distributions. They have similar spectral types (K7-M1) and are at approximately the same evolutionary stage, allowing comparison of the four stars in the two systems. We conclude that S CrA and VV CrA are young binary systems of stars bridging the Class I and Class II evolutionary stages, characterized by high accretion luminosities and variable emission lines.