CO Fundamental Emission from V836 Tau

TL;DR

This study analyzes high-resolution CO emission spectra from V836 Tau, revealing unusual double-peaked profiles indicating emission from a very restricted disk region, which informs understanding of disk dissipation processes.

Contribution

It provides the first detailed high-resolution CO fundamental spectroscopy of V836 Tau, showing that CO emission originates from a smaller disk region than typical T Tauri stars, suggesting disk truncation or excitation effects.

Findings

CO emission arises from within 0.5 AU of the star

CO line profiles are markedly double-peaked

Implications for disk truncation or excitation effects

Abstract

We present high resolution 4.7 micron CO fundamental spectroscopy of V836 Tau, a young star with properties that are between those of classical and weak T Tauri stars and which may be dissipating its circumstellar disk. We find that the CO line profiles of V836 Tau are unusual in that they are markedly double-peaked, even after correcting for stellar photospheric absorption in the spectrum. This suggests that the CO emission arises from a restricted range of disk radii (< 0.5 AU), in contrast to the situation for most classical T Tauri stars where the CO emission extends out to much larger radii (~ 1-2 AU). We discuss whether the outer radius of the emission in V836 Tau results from the physical truncation of the disk or an excitation effect. We also explore how either of these hypotheses may bear on our understanding of disk dissipation in this system.