Gas kinematics of key prebiotic molecules in GV Tau N revealed with an ALMA, PdBI, and Herschel synergy

TL;DR

This study uses multi-wavelength observations to reveal the complex gas kinematics, morphology, and chemistry of the GV Tau N system, including the first detection of water, indicating a binary with an inclined disc and outflows.

Contribution

It provides the first high-resolution images of the gas and dust in GV Tau N, revealing a binary system with a disrupted disc and outflows, and detects water emission for the first time in this source.

Findings

Detection of water emission towards GV Tau N.

Identification of a gaseous disc, jet, and outflows at high resolution.

Evidence supporting a binary system with an inclined disc.

Abstract

A large effort has been made to detect warm gas in the planet formation zone of circumstellar discs using space and ground-based near infrared facilities. GV Tau N, the most obscured component of the GV Tau system, is an outstanding source, being one of the first targets detected in HCN and the only one detected in CH$_4$ so far. Although near infrared observations have shed light on its chemical content, the physical structure and kinematics of the circumstellar matter remained unknown. We use interferometric images of the HCN 3-2 and $^{13}$CO 3-2 lines, and far-IR observations of $^{13}$CO, HCN, CN and H$_2$O transitions to discern the morphology, kinematics, and chemistry of the dense gas close to the star. These observations constitute the first detection of H$_2$O towards GV Tau N. Moreover, ALMA high spatial resolution (~ 7 au) images of the continuum at 1.1 mm and the HCN 3-2 line resolve different gas components towards GV Tau N, a gaseous disc with R~25 au, an ionized jet, and one (or two) molecular outflows. The asymmetric morphology of the gaseous disc shows that it has been eroded by the jet. All observations can be explained if GV Tau N is binary, and the primary component has a highly inclined individual disc relative to the circumbinary disc. We discuss the origin of the water and the other molecules emission according to this scenario. In particular, we propose that the water emission would come from the disrupted gaseous disc and the molecular outflows.