RECURRENT PLANET FORMATION AND INTERMITTENT PROTOSTELLAR OUTFLOWS INDUCED BY EPISODIC MASS ACCRETION
RECURRENT PLANET FORMATION AND INTERMITTENT PROTOSTELLAR OUTFLOWS INDUCED BY EPISODIC MASS ACCRETION
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DOI：
10.1088/0004-637x/729/1/42
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
M. Machida;S. Inutsuka;Tomoaki Matsumoto
中科院分区：
文献类型：
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作者：
M. Machida;S. Inutsuka;Tomoaki Matsumoto
从星际核心阶段到原恒星形成后约 104 年，研究了磁化云核中星周盘的形成和演化。在星周盘中，由于磁不活跃区域的引力不稳定，首先发生碎裂，并出现亚恒星质量的物体。亚恒星质量天体通过与巨大星周盘的引力相互作用而失去轨道角动量，最终落到原恒星上。在这次坠落之后，星周盘通过质量吸积增加其质量，并再次引起碎片。亚恒星质量天体的形成和坠落在星周盘中不断重复，直到主要吸积阶段结束。在此过程中，碎片的质量仍然很小，因为星周盘在变得非常大之前，会因碎片和随后碎片的坠落而失去质量。此外，当碎片在原恒星附近运行时，它们会扰乱内盘区域并促进原恒星上的质量吸积。亚恒星质量天体的轨道运动明显与原恒星吸积光度的时间变化同步。此外，当物体坠落时，原恒星会在短时间内表现出强烈的增亮。间歇性的原恒星流出也是由星周盘驱动的，由于碎片的轨道运动，星周盘的磁力线高度混乱。随时间变化的原恒星光度和间歇性流出可能是探测星周盘中行星质量物体的线索。
The formation and evolution of a circumstellar disk in magnetized cloud cores are investigated from a prestellar core stage until ∼104 yr after protostar formation. In the circumstellar disk, fragmentation first occurs due to gravitational instability in a magnetically inactive region, and substellar-mass objects appear. The substellar-mass objects lose their orbital angular momenta by gravitational interaction with the massive circumstellar disk and finally fall onto the protostar. After this fall, the circumstellar disk increases its mass by mass accretion and again induces fragmentation. The formation and falling of substellar-mass objects are repeated in the circumstellar disk until the end of the main accretion phase. In this process, the mass of the fragments remains small, because the circumstellar disk loses its mass by fragmentation and subsequent falling of fragments before it becomes very massive. In addition, when fragments orbit near the protostar, they disturb the inner disk region and promote mass accretion onto the protostar. The orbital motion of substellar-mass objects clearly synchronizes with the time variation of the accretion luminosity of the protostar. Moreover, as the objects fall, the protostar shows a strong brightening for a short duration. The intermittent protostellar outflows are also driven by the circumstellar disk whose magnetic field lines are highly tangled owing to the orbital motion of fragments. The time-variable protostellar luminosity and intermittent outflows may be a clue for detecting planetary-mass objects in the circumstellar disk.