Metal pollution of low-mass Population III stars through accretion of interstellar objects like ‘Oumuamua
Metal pollution of low-mass Population III stars through accretion of interstellar objects like ‘Oumuamua
复制标题
DOI：
10.1093/pasj/psy075
复制
发表时间：
2018-04
影响因子：
2.3
通讯作者：
A. Tanikawa;T. Suzuki;Y. Doi
中科院分区：
文献类型：
--
作者：
A. Tanikawa;T. Suzuki;Y. Doi
我们计算了像Oumuamua这样的星际天体（ISO）在低质量第III星族恒星上的吸积质量（Pop.~ III幸存者），并估计Pop.~三个幸存者。根据Oumuamua的发现估计的ISO数密度是如此之高（$\sim 0.2 $~Au $^{-3}$），III幸存者有机会在碰撞与ISO $\gtrsim 10^5 $次每$1 $~Gyr。“Oumuamua本身将在Pop附近升华。III幸存者，因为它的体积小，$\sim 100 $~m。然而，大小为$\gtrsim 3 $~km的ISO将达到Pop.~三名幸存者浮出水面。假设一个大于$D $的ISO累积数密度为$n\propto D ^{-\alpha}$，Pop.~ III型幸存者可以增加ISO质量$\gtrsim 10 ^{-16} M_\odot $，或ISO铁质量$\gtrsim 10 ^{-17} M_\odot $，如果$\alpha 4 $，Pop.~ III幸存者没有机会与$D\gtrsim 3 $~km的ISO碰撞，并保持无金属。如果$3 <\alpha <4 $，Pop.~ III类幸存者受ISO污染最严重，达到[Fe/H]$\sim-7 $。如果$\alpha <3 $直到$D\sim 10 $~km，则Pop.~ III幸存者可能隐藏在迄今发现的贫金属恒星中。噗~ III幸存者将随着银河系中心距离的减小而受到更多的污染。虽然金属污染取决于$\alpha $和银河中心距离，但我们首先展示了ISO对Pop金属污染的重要性。三个幸存者。
We calculate accretion mass of interstellar objects (ISOs) like `Oumuamua onto low-mass population III stars (Pop.~III survivors), and estimate surface pollution of Pop.~III survivors. An ISO number density estimated from the discovery of `Oumuamua is so high ($\sim 0.2$~au$^{-3}$) that Pop.~III survivors have chances at colliding with ISOs $\gtrsim 10^5$ times per $1$~Gyr. `Oumuamua itself would be sublimated near Pop.~III survivors, since it has small size, $\sim 100$~m. However, ISOs with size $\gtrsim 3$~km would reach the Pop.~III survivor surfaces. Supposing an ISO cumulative number density with size larger than $D$ is $n \propto D^{-\alpha}$, Pop.~III survivors can accrete ISO mass $\gtrsim 10^{-16}M_\odot$, or ISO iron mass $\gtrsim 10^{-17}M_\odot$, if $\alpha 4$, Pop.~III survivors have no chance at colliding with ISOs with $D \gtrsim 3$~km, and keep metal-free. If $3 < \alpha < 4$, Pop.~III survivors would be most polluted by ISOs up to [Fe/H] $\sim -7$. If $\alpha < 3$ up to $D \sim 10$~km, Pop.~III survivors could hide in metal-poor stars so far discovered. Pop.~III survivors would be more polluted with decreasing the Galactocentric distance. Although the metal pollution depends on $\alpha$ and the Galactocentric distance, we first show the importance of ISOs for the metal pollution of Pop.~III survivors.