MINDS. JWST-MIRI Observations of a Spatially Resolved Atomic Jet and Polychromatic Molecular Wind Toward SY Cha

TL;DR

This study uses JWST MIRI-MRS observations to detect and analyze a spatially resolved molecular wind in the young stellar object SY Cha, revealing properties of the disk wind and its potential role in angular momentum removal.

Contribution

First polychromatic detection of extended H2 in a moderately inclined Class II source, providing new insights into disk wind characteristics and mass loss rates.

Findings

Detected extended H2 and [Ne II] emission toward SY Cha

Measured high temperature and wide semi-opening angle of the H2 emission

Derived a molecular wind mass loss rate of 3±2×10⁻⁹ Msun/yr

Abstract

The removal of angular momentum from protostellar systems drives accretion onto the central star and may drive the dispersal of the protoplanetary disk. Winds and jets can contribute to removing angular momentum from the disk, though the dominant process remain unclear. To date, observational studies of resolved disk winds have mostly targeted highly inclined disks. We report the detection of extended H2 and [Ne II] emission toward the young stellar object SY Cha with the JWST Mid-InfraRed Instrument Medium Resolution Spectrometer (MIRI-MRS). This is one of the first polychromatic detections of extended H2 toward a moderately inclined, i=51.1 degrees, Class II source. We measure the semi-opening angle of the H2 emission as well as build a rotation diagram to determine the H2 excitation temperature and abundance. We find a wide semi-opening angle, high temperature, and low column density for the H2 emission, all of which are characteristic of a disk wind. We derive a molecular wind mass loss rate of 3+-2e-9 Msun/yr, which is high compared to the previously derived stellar accretion rate of 6.6e-10 Msun/yr. This suggests either that the stellar accretion and the disk wind are driven by different mechanisms or that accretion onto the star is highly variable. These observations demonstrate MIRI-MRS's utility in expanding studies of resolved disk winds beyond edge-on sources.