ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Deriving Inclination Angle and Velocity of the Protostellar Jets from Their SiO Knots

Abstract

We have selected six sources (G209.55–19.68S2, G205.46–14.56S1 - A, G203.21–11.20W2, G191.90–11.21S, G205.46–14.56S3, and G206.93–16.61W2) from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP), in which these sources have been mapped in the CO ( J = 2−1), SiO ( J = 5−4), and C 18 O ( J = 2−1) lines. These sources have high-velocity SiO jets surrounded by low-velocity CO outflows. The SiO jets consist of a chain of knots. These knots have been thought to be produced by semiperiodic variations in jet velocity. Therefore, we adopt a shock-forming model, which uses such variations to estimate the inclination angle and velocity of the jets. We also derive the inclination angle of the CO outflows using the wide-angle wind-driven shell model and find it to be broadly consistent with that of the associated SiO jets. In addition, we apply this shock-forming model to another three protostellar sources with SiO jets in the literature—HH 211, HH 212, and L1448C(N)—and find that their inclination angle and jet velocity are consistent with those previously estimated from proper-motion and radial-velocity studies.