用SPHERE/ZIMPOL对Z CMa喷流进行亚0.1”光学成像
Sub-0.1" optical imaging of the Z CMa jets with SPHERE/ZIMPOL
摘要：
年轻恒星中质量吸积-喷射的关键信息可以从具有周期性吸积爆发的源中喷流的高空间分辨率图像中获得。使用SPHERE/ZIMPOL仪器，我们观测到年轻的双星Z CMa，它由一颗Herbig Be星和一颗FUor天体组成，两者都驱动着一个喷流。我们分析了这两个喷气机的结构与以前在这个目标中观察到的吸积事件。我们在Halalpha和OI 6300 A线上以前所未有的~0.03 arcsec的角分辨率获得了光学图像，在此基础上我们进行了连续减法和反卷积，从而得出了相互一致的结果。我们的图像显示从两个来源的扩展发射：一个相当紧凑和准直性差的Herbig组件和扩展的准直和旋进射流从FUor组件发射SW。来自赫比格星的紧凑发射与广角风兼容，并且可能与最近的爆发事件有关。FUor喷流被追踪到距离源70 mas（80 AU），高度准直，宽度为26-48 AU，距离为100-200 AU，这与金牛座T星的喷流宽度相似。这有力地表明，同样的磁离心喷射发射机制也在FUOR中运行。所观察到的喷流摆动可以被模拟为起源于一个轨道运动，周期为4.2年，围绕一个看不见的同伴，质量在0.48和1 Msun之间。喷流质量损失率Mloss是从OI光度中得出的，范围在1 E-8和1 E-6 Msun/yr之间。这是第一次直接测量从射流在一个FUor。如果我们假设先前通过吸积盘模型获得的Macc估计值，则导出的Mloss范围将意味着非常低的质量喷射效率（Mloss/Macc < 0.02），低于金牛T星的典型值。
英文摘要：
Crucial information on the mass accretion-ejection in young stars can be obtained from high spatial resolution images of jets in sources with recurrent accretion outbursts. Using the SPHERE/ZIMPOL instrument, we observed the young binary Z CMa that is composed of a Herbig Be star and a FUor object, both driving a jet. We analyse the structure of the two jets in relation with previous accretion events observed in this target. We obtained optical images in the Halpha and OI 6300A lines at the unprecedented angular resolution of ~0.03 arcsec, on which we have performed both continuum subtraction and deconvolution, thereby deriving results that are consistent with each other. Our images reveal extended emission from both sources: a fairly compact and poorly collimated emission SW of the Herbig component and an extended collimated and precessing jet from the FUor component. The compact emission from the Herbig star is compatible with a wide-angle wind and is possibly connected to the recent outburst events shown by this component. The FUor jet is traced down to 70 mas (80 AU) from the source and is highly collimated with a width of 26-48 AU at distances 100-200 AU, which is similar to the width of jets from T Tauri stars. This strongly suggests that the same magneto-centrifugal jet-launching mechanism also operates in FUors. The observed jet wiggle can be modelled as originating from an orbital motion with a period of 4.2 yr around an unseen companion with mass between 0.48 and 1 Msun. The jet mass loss rate Mloss was derived from the OI luminosity and is in the range 1E-8 and 1E-6 Msun/yr. This is the first direct Mloss measurement from a jet in a FUor. If we assume previous Macc estimates obtained through modelling of the accretion disk, the derived range of Mloss would imply a very low mass-ejection efficiency (Mloss/Macc < 0.02), which is lower than that typical of T Tauri stars.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
