arXiv 2112.126402021-12astro-ph.GA

脱边--长丝和端芯同时成型

Taking off the edge -- simultaneous filament and end core formation

Stefan Heigl, Elena Hoemann, Andreas Burkert

DOI：: 10.1093/mnras/stac3110

摘要：

有限长度的理想化的星形形成细丝的模拟通常显示核心生长，其由在其各自端部形成的两个核心主导。端芯的形成是由于在细丝端部处的强增加的加速度，这导致在细丝沿着其轴线塌陷期间材料的扫掠。由于这种生长模式通常比长丝中的任何其他芯形成模式更快，因此与长丝内部形成的其他芯相比，端部芯通常在质量和密度上占主导地位。然而，对恒星形成丝状体的观察并没有显示丝状体末端的核心的这种普遍性。我们探讨了一种可能的机制，以减缓增长的最终核心使用数值模拟的同时长丝和嵌入式核心的形成，在我们的情况下，一个径向吸积长丝形成在一个有限的收敛流。虽然这样的设置仍然导致最终核心，但它们很快开始向内移动，并且通过材料的持续积累在核心外部形成密度梯度。结果，最外面的核心不再位于细丝的确切末端，并且密度梯度软化了核心的向内重力加速度。因此，两个端部芯不像预期的那样快速生长，并且因此不支配细丝中的其他芯形成模式。

英文摘要：

Simulations of idealised star-forming filaments of finite length typically show core growth which is dominated by two cores forming at its respective end. The end cores form due to a strong increasing acceleration at the filament ends which leads to a sweep-up of material during the filament collapse along its axis. As this growth mode is typically faster than any other core formation mode in a filament, the end cores usually dominate in mass and density compared to other cores forming inside a filament. However, observations of star-forming filaments do not show this prevalence of cores at the filament ends. We explore a possible mechanism to slow the growth of the end cores using numerical simulations of simultaneous filament and embedded core formation, in our case a radially accreting filament forming in a finite converging flow. While such a setup still leads to end cores, they soon begin to move inwards and a density gradient is formed outside of the cores by the continued accumulation of material. As a result, the outermost cores are not longer located at the exact ends of the filament and the density gradient softens the inward gravitational acceleration of the cores. Therefore, the two end cores do not grow as fast as expected and thus do not dominate over other core formation modes in the filament.

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