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arXiv 2003.01806astro-ph.SR
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年轻恒星系统中环双星盘外流中主喷流的性质

The nature of a primary jet within a circumbinary disc outflow in a young stellar system

Chris J. R. Lynch, Michael D. Smith

摘要:

大多数恒星形成于双星系统中,两颗恒星都可能通过从环双星盘吸积物质到它们的个人盘上而成长。我们猜想,在许多情况下,一个宽的分子风将包围一个准直的原子喷流从靠近轨道运行的年轻恒星。在这里探索所谓的Circumbinary Scenario,以找到共同的可识别属性。动力学设置研究与三维模拟化学和冷却。我们提取了100 AU量级的性质,并与风和喷流源在轨道上的共轨情景进行了比较。我们发现,快速的轨道运动产生一个广泛的电离鞘周围的射流核心与一个大的开口角在基地。这与周围分子外流的存在无关。然而,当分子流出限制周围介质的运动时,原子射流被压缩到~ 55 AU以上,而周围介质反过来又限制了射流。这些物理特性被传递到光学H-α成像,提供了一种区分模型的方法。通过下一代仪器,可以在这些尺度上探索高激发鞘层和再结晶区。然而,一般来说,电离物质的数量和位置,无论是在结还是鞘中,都将取决于几个参数,包括轨道周期,轴对准和脉冲幅度。

英文摘要:

Most stars form in binaries, and both stars may grow by accreting material from a circumbinary disc onto their personal discs. We suspect that in many cases a wide molecular wind will envelope a collimated atomic jet emanating from close to an orbiting young star. This so-called Circumbinary Scenario is explored here in order to find common identifiable properties. The dynamical set up is studied with three dimensional simulations with chemistry and cooling included. We extract the properties on scales of order 100\,AU and compare to the Co-Orbital Scenario in which the wind and jet sources are in orbit. We find that the rapid orbital motion generates a wide ionised sheath around the jet core with a large opening angle at the base. This is independent of the presence of the surrounding molecular outflow. However, the atomic jet is recollimated beyond ~ 55 AU when the molecular outflow restricts the motion of the ambient medium which, in turn, confines the jet. These physical properties are relayed to the optical H-alpha imaging, providing a means of distinguishing between models. The high excitation sheath and recollimation region can be explored on these scales through the next generation of instruments. However, in general, the amount and location of the ionised material, whether in the knots or the sheath, will depend on several parameters including the orbital period, axis alignment and pulse amplitude.

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