ORPHANED PROTOSTARS
ORPHANED PROTOSTARS
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孤儿原恒星
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Valtonen
中科院分区：
文献类型：
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作者：
B. Reipurth;S. Mikkola;M. Connelley;M. Valtonen
我们探索了康奈利和他的同事最近发现的一组遥远的伴星(∼1000-5000 AU)到I类原恒星源的起源，他们注意到伴星比例随着源的演化而减少。在这里，我们介绍了嵌入致密云核的不稳定三元系的N体模拟。许多伴星被弹射到未受约束的轨道上，并迅速逃逸，但其他的被弹射时，动量不足，无法爬出云核和相关双星的势井。这些松散的伴星到达几千个天文单位的距离，然后掉落，最终随着云核的逐渐消失而被抛出逃逸。我们使用术语孤儿来表示从胎盘云核动态抛出的原恒星物体，要么逃脱，要么在大间隔下被微弱地束缚一段时间。所有三重系统中有一半被发现在原恒星阶段解体，所以如果多个系统是一个云核坍塌的频繁结果，那么孤儿应该是常见的。束缚的孤儿与嵌入的近原恒星双星有关，但逃逸的孤儿在原恒星阶段可以旅行到∼0.2PC。从潜在的井中陡峭的攀登确保了孤儿在运动学上与出生在较少暴力的史前时期的年轻恒星没有什么不同。在严重灭绝的云核之外发现孤儿，将使人们能够详细研究林氏轨道上的原恒星，在近红外，在某些情况下，甚至在光学波长。
We explore the origin of a population of distant companions (∼1000–5000 AU) to Class I protostellar sources recently found by Connelley and coworkers, who noted that the companion fraction diminished as the sources evolved. Here, we present N-body simulations of unstable triple systems embedded in dense cloud cores. Many companions are ejected into unbound orbits and quickly escape, but others are ejected with insufficient momentum to climb out of the potential well of the cloud core and associated binary. These loosely bound companions reach distances of many thousands of AU before falling back and eventually being ejected into escapes as the cloud cores gradually disappear. We use the term orphans to denote protostellar objects that are dynamically ejected from their placental cloud cores, either escaping or for a time being tenuously bound at large separations. Half of all triple systems are found to disintegrate during the protostellar stage, so if multiple systems are a frequent outcome of the collapse of a cloud core, then orphans should be common. Bound orphans are associated with embedded close protostellar binaries, but escaping orphans can travel as far as ∼0.2 pc during the protostellar phase. The steep climb out of a potential well ensures that orphans are not kinematically distinct from young stars born with a less violent pre-history. The identification of orphans outside their heavily extincted cloud cores will allow the detailed study of protostars high up on their Hayashi tracks at near-infrared and in some cases even at optical wavelengths.