Modeling the gas reservoir of circumstellar disks around young G-type stars
Modeling the gas reservoir of circumstellar disks around young G-type stars
复制标题
模拟年轻 G 型恒星周围星周盘的气体储层
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Fatima Sammar
中科院分区：
文献类型：
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作者：
I. Kamp;Fatima Sammar
如果没有一个模型来描述这些盘的化学结构，用盘的质量来解释年轻G型恒星周围纤细的星周盘中的分子线观测是很困难的。本文讨论了化学在周围的年轻的太阳型恒星的盘模型的基础上，考虑到恒星色球的存在。以一颗7000万年前的太阳型星星为例，它周围的盘显示出色球层的离解辐射强于距离星星2000 Au的星际紫外辐射场。与该研究领域的其他研究类似，发现由于光解离作用，分子云的CO/H2比远未达到10 - 4的标准值。此外，尘埃与气体的质量比以及尘埃颗粒大小起着重要的作用，在这些磁盘的H2丰度。
Interpretation of molecular line observations in tenuous circumstellar disks around young G-type stars in terms of a disk mass is difficult without a model that describes the chemical structure of these disks. This paper discusses the chemistry in tenuous disks around young solar-type stars based on disk models that take into account the presence of a stellar chromosphere. The example of the disk around a 70 Myr old solar-type star shows that the dissociating radiation from the chromosphere is stronger than the interstellar ultraviolet radiation field up to a distance of ∼400 AU from the star. Similar to other studies in this research field, it is found that, due to photodissociation, the CO-to-H 2 ratio is far from the canonical value of 10 -4 for molecular clouds. Moreover, the dust-to-gas mass ratio as well as the dust grain size plays an important role for the H 2 abundance in these disks.