标题： 大质量恒星触发的恒星形成 显示英文标题

标题： Triggered Star Formation by Massive Stars

摘要： 我们提出了对大质量恒星在OB星协（Λ Ori区域、猎户座OB1和鹿豹座OB1星协）中的低质量和中等质量恒星形成过程中所起作用的诊断。我们发现，经典的T Tauri星和Herbig Ae/Be星倾向于排列在明亮的O型星与明亮边缘或彗星状云之间；越靠近云，它们就越年轻。我们的位置和时间研究支持辐射驱动塌缩机制的有效性，在该机制中，明亮O型星的Lyman连续光子会形成扩展的电离前沿，蒸发并压缩附近的云团成为明亮边缘或彗星状云。随后的冲击压力导致密集团块坍缩，在云表面（即明亮边缘）形成低质量恒星，并在云内部稍深处形成中等质量恒星。这些恒星是当前恒星形成的一个标志；未见年轻恒星引导电离前沿进一步深入云内。明亮边缘或彗星状云中的年轻恒星可能由触发机制形成，这将导致成员恒星或恒星群之间的年龄跨度达到数百万年。 显示英文摘要

摘要： We present our diagnosis of the role that massive stars play in the formation of low- and intermediate-mass stars in OB associations (the Lambda Ori region, Ori OB1, and Lac OB1 associations). We find that the classical T Tauri stars and Herbig Ae/Be stars tend to line up between luminous O stars and bright-rimmed or comet-shaped clouds; the closer to a cloud the progressively younger they are. Our positional and chronological study lends support to the validity of the radiation-driven implosion mechanism, where the Lyman continuum photons from a luminous O star create expanding ionization fronts to evaporate and compress nearby clouds into bright-rimmed or comet-shaped clouds. Implosive pressure then causes dense clumps to collapse, prompting the formation of low-mass stars on the cloud surface (i.e., the bright rim) and intermediate-mass stars somewhat deeper in the cloud. These stars are a signpost of current star formation; no young stars are seen leading the ionization fronts further into the cloud. Young stars in bright-rimmed or comet-shaped clouds are likely to have been formed by triggering, which would result in an age spread of several megayears between the member stars or star groups formed in the sequence.