A triple star in disarray -- Multi-epoch observations of T Tauri with VLT-SPHERE and LBT-LUCI

TL;DR

This study uses multi-epoch high-resolution imaging and molecular hydrogen mapping to analyze the complex outflow system of the enigmatic triple star T Tauri, revealing new features and clarifying the roles of its components.

Contribution

The paper provides new high-resolution imaging and H2 emission maps of T Tauri, identifying outflow features and the dynamic behavior of its stellar components for the first time.

Findings

T Tauri Sb drives the southeast-northwest outflow.

T Tauri Sb has faded due to increased extinction.

T Tauri Sa has brightened and is detected in J-band for the first time.

Abstract

T Tauri remains an enigmatic triple star for which neither the evolutionary state of the stars themselves, nor the geometry of the complex outflow system is completely understood. Eight-meter class telescopes equipped with state-of-the-art adaptive optics provide the spatial resolution necessary to trace tangential motion of features over a timescale of a few years, and they help to associate them with the different outflows. We used J-, H-, and K-band high-contrast coronagraphic imaging with VLT-SPHERE recorded between 2016 and 2018 to map reflection nebulosities and obtain high precision near-infrared (NIR) photometry of the triple star. We also present molecular hydrogen emission maps of the 1-0 S(1) line at 2.122 micron obtained with LBT-LUCI during its commissioning period at the end of 2016. The data reveal a number of new features in the system, some of which are seen in reflected light and some are seen in H2 emission; furthermore, they can all be associated with the main outflows. The tangential motion of the features provides compelling evidence that T Tauri Sb drives the southeast-northwest outflow. T Tauri Sb has recently faded probably because of increased extinction as it passes through the southern circumbinary disk. While T Tauri Sb is approaching periastron, T Tauri Sa instead has brightened and is detected in all our J-band imagery for the first time.