Inefficient Growth of SiOx Grains: Implications for Circumstellar Outflows
Inefficient Growth of SiOx Grains: Implications for Circumstellar Outflows
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DOI：
10.3847/2041-8213/ac8002
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发表时间：
2022-07-01
影响因子：
7.9
通讯作者：
Nuth, Joseph A., III
中科院分区：
文献类型：
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作者：
Kimura, Yuki;Tanaka, Kyoko K.;Nuth, Joseph A., III
为了解释大量的星周尘埃和高恒星风速的观测结果，大多数模型简单地假设硅酸盐尘埃粒子有效的成核和生长。在这里，我们报告的SiO-（SiOx）（n）颗粒粘附系数的测量在微重力探空火箭实验，表明非常低效（0.005-0.016）从蒸汽颗粒形成。将这一测量应用于富氧渐近巨星分支星的辐射驱动风表明，初始的颗粒凝聚体种群应该由非常大量的非常微小的尘埃粒子组成。这些尘埃的聚集将产生低维的分形聚集体，这些聚集体应该与恒星辐射场很好地耦合，并有效地驱动恒星质量损失。
To explain observations of abundant circumstellar dust and high stellar wind velocity, most models simply postulate the efficient nucleation and growth of silicate dust particles. Here, we report measurement of the SiO-(SiOx)(n) grain sticking coefficient in a microgravity sounding rocket experiment, indicating very inefficient (0.005-0.016) grain formation from the vapor. Application of this measurement to radiative-driven winds in oxygen-rich asymptotic giant branch stars indicates that the initial grain condensate population should consist of very tiny dust particles in very large numbers. Aggregation of this dust population will produce low-dimension fractal aggregates that should couple well to the stellar radiation field and efficiently drive stellar mass loss.