An outflow origin of the [NeII] emission in the T Tau triplet

TL;DR

This study shows that the [NeII] emission in the T Tau triplet mainly originates from outflows and shocks rather than the disk surface, challenging previous assumptions about its origin.

Contribution

The paper provides high-resolution spatial and spectral evidence that [NeII] emission in T Tau is primarily from outflows, not the disk surface, highlighting the role of jets in [NeII] emission.

Findings

[NeII] emission is centered on T Tau S with a large spatial extent.

Detected extended red- and blue-shifted [NeII] emission associated with outflows.

Only a small part of [NeII] emission relates directly to the X-ray bright component.

Abstract

(Note: this is a shortened version of the original "structured" (A&A format) abstract.) The 12.81 micrometer [NeII] line has recently gained interest as a potential tracer of gas in the tenuous surface layers of circumstellar disks. The line has been detected using the Spitzer Space Telescope in many young stars, yet these observations neiter spatially nor spectrally resolve the [NeII emission, leaving the nature of the emission mechanism unclear. Both an origin in an X-ray irradiated disk surface and an origin in strong, dissociative shocks have been proposed. We have performed a high spatial and spectral resolution (0.4 arcsec, R=30000) study of the T Tau triplet. This system contains three young stars with disks, at least one strong X-ray source (T Tau N), and diffuse regions of shocked gas surrounding the system on a scale of a few arcseconds. We find that the dominant component of [NeII] emission is centered on T Tau S and has a spatial extent of approximately 1.1 arcseconds, which is much larger than the disks in T Tau S. We detect spatially extended red-shifted emission NW of the system and fainter blue-shifted emission to the SE, which we associate with the N-S outflow from T Tau S. Only a small fraction of the [NeII] emission appears to be directly related to the X-ray bright northern component. We propose [NeII] emission in jets as a major factor causing the observed large scatter in the X-ray luminosity vs. [NeII] luminosity relation. We argue that T Tau S is the driving source of the T Tau "NW-blob"