Velocity-resolved [Ne III] from X-Ray Irradiated Sz 102 Microjets

TitleVelocity-resolved [Ne III] from X-Ray Irradiated Sz 102 Microjets
Publication TypeJournal Article
Year of Publication2014
AuthorsLiu, C-F, Shang, H, Walter, F M, Herczeg, G J
KeywordsISM: individual: Sz 102, ISM: jets and outflows, ISM: kinematics and dynamics, stars: mass-loss, stars: pre-main sequence, X-rays: stars

{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] {$łambda$}3869 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 {\ap} 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. Optical line ratios indicate that the microjets are hot (T łt}\~{} 1.6 {\times} 10⁴ K) and ionized (n$_{e}$ {\gt}\~{} 5.7 {\times} 10⁴ cm$^{-3}$). The blueshifted component has \~{}13% higher temperature and \~{}46% higher electron density than the redshifted counterpart, forming a system of an asymmetric pair of jets. The detection of the [Ne III] {$łambda$}3869 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] {$łambda$}3869 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. Future high-sensitivity X-ray imaging and high angular-resolution optical spectroscopy may help confirm the picture proposed. }