Spatially resolved mid-infrared observations of the triple system T Tauri

TL;DR

This study uses mid-infrared interferometry and modeling to analyze the dust distribution and disc orientations in the T Tauri triple system, revealing distinct disc geometries and dust processing signs around each component.

Contribution

It provides the first detailed mid-infrared spatially resolved observations and modeling of the individual circumstellar discs in the T Tauri triple system, including the misaligned discs around T Tau N and S.

Findings

Extended mid-infrared emission around all components

Face-on disc around T Tau N with silicate emission

Edge-on disc around T Tau Sa with silicate absorption

Abstract

To enhance our knowledge of the characteristics and distribution of the circumstellar dust associated with the individual components of the young hierarchical triple system T Tau, observations in the N-band with MIDI at the VLTI were performed. Our study is based on both the interferometric and the spectrophotometric measurements and is supplemented by new visual and infrared photometry. Also, the phases were investigated to determine the dominating mid-infrared source in the close southern binary. The data were fit with the help of a sophisticated physical disc model. This model utilises the radiative transfer code MC3D that is based on the Monte-Carlo method. Extended mid-infrared emission is found around all three components of the system. Simultaneous fits to the photometric and interferometric data confirm the picture of an almost face-on circumstellar disc around T Tau N. Towards this star, the silicate band is seen in emission. This emission feature is used to model the dust content of the circumstellar disc. Clear signs of dust processing are found. Towards T Tau S, the silicate band is seen in absorption. This absorption is strongly pronounced towards the infrared companion T Tau Sa as can be seen from the first individual N-band spectra for the two southern components. Our fits support the previous suggestion that an almost edge-on disc is present around T Tau Sa. This disc is thus misaligned with respect to the circumstellar disc around T Tau N. The interferometric data indicate that the disc around T Tau Sa is oriented in the north-south direction, which favours this source as launching site for the east-western jet. We further determine from the interferometric data the relative positions of the components of the southern binary.