标题： HH 212 中心 Knots 的 H2 速度结构：不对称性和旋转 显示英文标题

标题： The H2 velocity structure of inner knots in HH 212: asymmetries and rotation

摘要： 对高度对称的原恒星外流 HH 212 内部结的高分辨率（R ~ 50 000）长缝光谱观测是在 H2 的 1-0 S(1) 线（2.12 微米）中获得的，空间分辨率为 ~0.45 角秒。 在由此产生的约 6 公里每秒的速度分辨率下，北部第一个结 NK1 的多次定向观测清楚地显示出双峰线轮廓，这与辐射弓激波或双（前向和反向）激波一致。 相比之下，南部第一个结 SK1 的速度分布仍为单峰，表明喷流速度显著较低，并且可能与南部流中的喷流脉冲相比，北部流中的密度变化有所不同。 与弓激波发射的半经验分析模型进行比较，使我们能够限制诸如弓激波相对于视线的倾角、每个流的弓激波和喷流速度等参数。 尽管该模型未能重现某些特征，但它确认了 HH 212 双极喷流两侧之间存在多种动力学和运动学不对称性。 这两个结的位置-速度图显示了复杂的动力学，大致与弓激波和/或喷流激波的发射一致，虽然 HH 212 中没有明确的喷流旋转标志，但并不排除喷流旋转的可能性。 这些结径向速度的变化以及其他流动之间的速度不对称性的替代解释，例如喷流方向的变化，也被考虑在内。 每个流中的流动速度和集束化之间存在相关性的可能性被提出。 显示英文摘要

摘要： High-resolution R~50 000 long-slit spectroscopy of the inner knots of the highly symmetrical protostellar outflow HH 212 was obtained in the 1-0 S(1) line of H2 at 2.12 micron with a spatial resolution of ~0.45 arcsec. At the resulting velocity resolution of ~6 km s-1, multiple slit oriented observations of the northern first knot NK1 clearly show double-peaked line profiles consistent with either a radiative bow shock or dual (forward and reverse) shocks. In contrast, the velocity distribution of the southern first knot SK1 remains single-peaked, suggesting a significantly lower jet velocity and possibly a different density variation in the jet pulses in the southern flow compared to the northern flow. Comparison with a semi-empirical analytical model of bow shock emission allows us to constrain parameters such as the bow inclination to the line of sight, the bow shock and jet velocities for each flow. Although a few features are not reproduced by this model, it confirms the presence of several dynamical and kinematical asymmetries between opposite sides of the HH 212 bipolar jet. The position-velocity diagrams of both knots exhibit complex dynamics that are broadly consistent with emission from a bow shock and/or jet shock, which does not exclude jet rotation, although a clear signature of jet rotation in HH 212 is missing. Alternative interpretations of the variation of radial velocity across these knots, such as a variation in the jet orientation, as well as for the velocity asymmetries between the flows, are also considered. The presence of a correlation between flow velocity and collimation in each flow is suggested.