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Velocity-Resolved [Ne III] from X-ray Irradiated Sz 102 Microjets

Image Credit: Chun-Fan Liu and Hsien Shang

(a) Position–velocity (PV) diagram of the [Ne III] λ3869 line from Sz 102, after Gaussian decomposition. The emission corresponds to the blueshifted and redshifted microjets is shown in blue and red contours, respectively. The spectra have been binned every 10 km s⁻¹ and smoothed with Gaussian with σ_G = 1.0 pixel.
(b) Decomposed [Ne III] λ3869 line profiles normalized to the redshifted peak intensity. The blueshifted and redshifted emissions are shown as blue and red histograms, respectively. For each decomposed line profile, a single Gaussian is fitted and is shown as blue and red thick lines, respectively.

Neon emission lines are good indicators of high-excitation regions close to a young stellar system because of their high ionization potentials and large critical densities. We have discovered [Ne III] λ3869 emission from the microjets of Sz 102, a low-mass young star in Lupus III. Spectroastrometric analyses of two-dimensional [Ne III] spectra obtained from archival high-dispersion (R ≈ 33,000) Very Large Telescope/UVES data suggest that the emission consists of two velocity components spatially separated by ∼0".3, or a projected distance of ∼60 AU. The stronger redshifted component is centered at ∼+21 km s⁻¹ with a line width of ∼140 km s⁻¹, and the weaker blueshifted component at ∼−90 km s⁻¹ with a line width of ∼190 km s⁻¹. The two components trace velocity centroids of the known microjets and show large line widths that extend across the systemic velocity, suggesting their potential origins in wide-angle winds that may eventually collimate into jets. The detection of the [Ne III] λ3869 line with the distinct velocity profile suggests that the emission originates in flows that may have been strongly ionized by deeply embedded hard X-ray sources, most likely generated by magnetic processes. The discovery of [Ne III] λ3869 emission along with other optical forbidden lines from Sz 102 supports the picture of wide-angle winds surrounding magnetic loops in the close vicinity of the young star. (Liu, Shang, Walter, & Herczeg 2014, ApJ, 786, 99)