论文标题
早期喷气机的行星星云中塑造“耳朵”
Shaping `Ears' in planetary nebulae by early jets
论文作者
论文摘要
我们进行了行星星云（PN）塑形的三维流体动力学模拟，并表明在主PN壳弹出之前的喷射会形成耳朵的形态特征。耳朵是主要星云的两个相反的突起，它们比主星云小，横截面从壳的耳朵的底部单调降低到其远端。只有一小部分的PNE有耳朵。短暂的喷气机在当前的模拟中大约一年，与常规的渐近巨型分支（AGB）风相互作用，形成耳朵，而后来吹出的密集风形成主PN密集的壳。也就是说，喷气机比主PN壳年龄要大。我们还发现，让喷气式耳朵充气，它们不能太活力，不能太宽，也不能太慢。短寿命喷射的流动结构可能是进入星云弹出的主要阶段几年或更短的，这可能是由于进入共同包膜演变的系统而产生的。低质量伴侣通过积聚磁盘积聚质量，并在进入PN的巨型祖细胞之星的信封之前发射喷气机。此后不久，伴侣进入信封并螺旋形，以弹出形成主PN外壳的信封。
We conduct three dimensional hydrodynamical numerical simulations of planetary nebula (PN) shaping and show that jets that precede the ejection of the main PN shell can form the morphological feature of ears. Ears are two opposite protrusions from the main nebula that are smaller than the main nebula and with a cross section that decreases monotonically from the base of an ear at the shell to its far end. Only a very small fraction of PNe has ears. The short-lived jets, about a year in the present simulations, interact with the regular asymptotic giant branch (AGB) wind to form the ears, while the later blown dense wind forms the main PN dense shell. Namely, the jets are older than the main PN shell. We also find that for the jets to inflate ears they cannot be too energetic, cannot be too wide, and cannot be too slow. A flow structure where short-lived jets precede the main phase of nebula ejection by a few years or less can result from a system that enters a common envelope evolution. The low mass companion accretes mass through an accretion disk and launches jets just before it enters the envelope of the giant progenitor star of the PN. Shortly after that the companion enters the envelope and spirals-in to eject the envelope that forms the main PN shell.
