The ablation barrier for the growth of metre-size objects in protoplanetary discs
The ablation barrier for the growth of metre-size objects in protoplanetary discs
复制标题
原行星盘中米级物体生长的烧蚀屏障
DOI：
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
H. Perets
中科院分区：
文献类型：
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作者：
Mor Rozner;Evgeni Grishin;H. Perets
烧蚀是一种破坏性的过程，它可以通过小型行星物体与气体环境的相互作用来侵蚀它们。消融在广泛的环境和各种条件下运行。在大气陨石进入地球-大气层和气体巨型行星包层中的行星小烧蚀的背景下，烧蚀得到了广泛的探索。在这里，我们表明，原行星盘中鹅卵石和小行星的消融可能对行星形成的早期阶段构成一个重要的障碍。我们使用解析计算表明，在原行星盘中普遍存在的条件下，小天体(分米--几十米)非常容易受到气体阻力的烧蚀。在这个大小范围内，消融可以有效地将小行星侵蚀到几厘米大小，并抑制这些小天体的进一步生长。因此，这给建议缓解米级障碍的渠道带来了潜在的困难。然而，一旦/如果圆盘中存在这样大的行星小星和行星胚胎，由烧蚀产生的1美元分米大小的鹅卵石种群可能会通过提高卵石吸积的效率而促进较大(>；公里大小)行星小行星和行星胚胎的生长。
Ablation is a destructive process which can erode small-size planetary objects through their interaction with a gaseous environment. Ablation operates in a wide range of environments and under various conditions. Ablation has been extensively explored in the context of atmospheric entries of meteorites into Earth-atmosphere and planetesimal ablation in gas-giant planetary envelopes. Here we show that ablation of pebbles and small planetesimals in protoplanetary-discs can constitute a significant barrier for the early stages of planet formation. We use analytic calculations to show that under the conditions prevailing in protoplanetary discs small bodies (decimetres -- tens of metres) are highly susceptible to gas-drag ablation. At this size-range ablation can efficiently erode the planetesimals down to few-cm size and quench any further growth of such small bodies. It thereby raises potential difficulties for channels suggested to alleviate the metre-size barrier. Nevertheless, the population of $\sim$decimetre-size pebbles resulting from ablation-erosion might boost the growth of larger (>km size) planetesimals and planetary embryos through increasing the efficiency of pebble-accretion, once/if such large planetesimals and planetary embryos exist in the disc.