巨大的行星可以通过圆盘的引力破碎而形成吗？
Can giant planets form by gravitational fragmentation of discs?
摘要：
引力碎裂被认为是在太阳型恒星附近的近轨道上形成巨行星的一种机制。然而，这一机制是否能在真实光盘的内部区域（R <40 AU）起作用还存在争议。我们使用一种新发展的方法来处理能量方程和状态方程，它占辐射转移效应的SPH模拟拱星盘。氢的不同化学和内部状态以及尘埃在不同密度和温度下的性质（低温下的冰覆盖尘埃颗粒、冰融化、尘埃升华）都被新方法考虑在内。我们提出了大质量拱星盘内部区域的辐射流体动力学模拟，并研究了两种情况：（i）由冷背景辐射场（T_bgr = 10K）照射的盘和（ii）由来自其中心恒星的辐射（T_bgr~1/R）加热的盘。在这两种情况下，圆盘都不会碎裂：前者是因为它不能足够快地冷却，而后者是因为它的引力不稳定。我们的结果（a）证实了以前的数值计算结果，使用不同的处理的流体力学和辐射转移，和（b）确认我们自己的早期分析预测。我们的结论是，盘碎片不太可能在半径小于40 AU的太阳型恒星周围产生巨行星。
英文摘要：
Gravitational fragmentation has been proposed as a mechanism for the formation of giant planets in close orbits around solar-type stars. However, it is debatable whether this mechanism can function in the inner regions (R<40 AU) of real discs. We use a newly developed method for treating the energy equation and the equation of state, which accounts for radiative transfer effects in SPH simulations of circumstellar discs. The different chemical and internal states of hydrogen and the properties of dust at different densities and temperatures (ice coated dust grains at low temperatures, ice melting, dust sublimation) are all taken into account by the new method.We present radiative hydrodynamic simulations of the inner regions of massive circumstellar discs and examine two cases: (i) a disc irradiated by a cool background radiation field (T_bgr=10K)and (ii) a disc heated by radiation from its central star (T_bgr~1/R). In neither case does the disc fragment: in the former because it cannot cool fast enough and in the latter because it is not gravitationally unstable. Our results (a) corroborate previous numerical results using different treatments for the hydrodynamics and the radiative transfer, and (b) confirm our own earlier analytic predictions. We conclude that disc fragmentation is unlikely to be able to produce giant planets around solar-type stars at radii <40 AU.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
