论文标题
在低质量恒星周围冰冷的死区中的超级地球形成
Formation of super-Earths in icy dead zones around low-mass stars
论文作者
论文摘要
尽管巨型行星的发生率随着恒星的质量而增加，但近距离地球的发生率降低。这与预期的是，行星的总质量在系统尺度上具有原球盘质量，因此是恒星质量的。由于雪线在行星形成过程中起着重要作用，因此我们检查了不同质量恒星周围原球电气盘温度结构的差异。原球盘可能在中平面上包含一个死区，该区域足够冷且致密，以抑制磁旋转不稳定。随着材料的积累，死区的外部可以通过自我加热。光盘中的温度可以低于远离恒星和死区内部的雪线温度。内部冰冷区域在较小的质量恒星周围具有较大的径向范围。固体冰冻材料的质量增加可能会使靠近低质量恒星的较大和更多的行星的原位形成。在内部冰冷区域中形成的超级毕业石可能具有包括大量挥发物的组成。
While giant planet occurrence rates increase with stellar mass, occurrence rates of close-in super-Earths decrease. This is in contradiction to the expectation that the total mass of the planets in a system scale with the protoplanetary disc mass and hence the stellar mass. Since the snow line plays an important role in the planet formation process we examine differences in the temperature structure of protoplanetary gas discs around stars of different mass. Protoplanetary discs likely contain a dead zone at the midplane that is sufficiently cold and dense for the magneto-rotational instability to be suppressed. As material builds up, the outer parts of the dead zone may be heated by self-gravity. The temperature in the disc can be below the snow line temperature far from the star and in the inner parts of a dead zone. The inner icy region has a larger radial extent around smaller mass stars. The increased mass of solid icy material may allow for the in situ formation of larger and more numerous planets close to a low-mass star. Super-Earths that form in the inner icy region may have a composition that includes a significant fraction of volatiles.
