Fine-Structure Line Emission from the Outflows of Young Stellar Objects

TL;DR

This study models the emission of fine-structure lines from young stellar object outflows, showing their dependence on jet parameters and X-ray luminosity, and predicting characteristic line shapes as jet signatures.

Contribution

It introduces detailed calculations of neon and oxygen line emissions from YSO outflows using the X-wind model, linking line luminosities to jet properties and X-ray activity.

Findings

NeII line luminosity can surpass disk model predictions at high accretion rates.

Line luminosities strongly correlate with mass-loss rate and X-ray luminosity.

Jet line profiles exhibit broad, blue-shifted features characteristic of jet emission.

Abstract

The flux and line shape of the fine-structure transitions of \NeII\ and \NeIII\ at 12.8 and 15.55\,$\mu$m and of the forbidden transitions of \OI\ $\lambda6300$ are calculated for young stellar objects with a range of mass-loss rates and X-ray luminosities using the X-wind model of jets and the associated wide-angle winds. For moderate and high accretion rates, the calculated \NeII\ line luminosity is comparable to or much larger than produced in X-ray irradiated disk models. All of the line luminosities correlate well with the main parameter in the X-wind model, the mass-loss rate, and also with the assumed X-ray luminosity --- and with one another. The line shapes of an approaching jet are broad and have strong blue-shifted peaks near the effective terminal velocity of the jet. They serve as a characteristic and testable aspect of jet production of the neon fine-structure lines and the \OI\ forbidden transitions.