Speaker
Description
HH 212 is a nearby protostellar jet driven by the Class 0 protostar IRAS 05413–0104, exhibiting a highly symmetric morphology with well-defined knot structures close to the disk. Previous ALMA observations have mapped HH 212 in the SiO J = 8–7 transition (Band 7). Here, we present the first high-resolution observations of the higher-J transition, SiO J = 16–15 (Band 9).
We find that the knots exhibit smaller Gaussian radii, narrower line widths, and lower brightness in Band 9 than in Band 7. These results can be understood if the jet has a decreasing radial density profile and a significant radial velocity component, as predicted by the X-wind model (Shu et al. 1995; Lee et al. 2022).
Assuming a radial density profile derived from the X-wind model, we construct a simple non-LTE model that reasonably reproduces the observed jet geometry and line ratios and highlights the importance of non-LTE effects in higher-J transitions. Our results confirm the previously adopted physical conditions in the innermost jet and provide further support for the X-wind model in generating protostellar jets.
| Participate the oral/poster presentation award competition | Yes |
|---|