标题： 极端压力下铁的熔化曲线：对行星核心的启示 显示英文标题

标题： The melting curve of iron at extreme pressures: implications for planetary cores

摘要： 类似地球质量的系外行星最近在太阳系外的系统中被发现。 为了理解它们的动力学，首先要了解的是它们是否拥有类似地球的液态金属核。 然而，在相当于数倍地球质量（对于质量为地球10倍（ME）的行星，压力超过1500 GPa）的条件下，铁的熔融曲线尚不清楚。 在那些超级地球核心的密度-温度区域，我们使用基于密度泛函理论的第一性原理分子动力学模拟计算了铁的熔融曲线。 通过将这条熔融曲线与超级地球的热结构计算结果进行比较，我们表明，质量大于2ME的行星具有固态核心，从而排除了内部由金属核驱动的磁场存在的可能性。 本研究获得的铁熔融曲线比任何已计算的行星绝热温度剖面更陡峭，这意味着随着类地行星尺寸的增大，存在液态金属核的可能性变得更小。 显示英文摘要

摘要： Exoplanets with masses similar to that of Earth have recently been discovered in extrasolar systems. A first order question for understanding their dynamics is to know whether they possess Earth like liquid metallic cores. However, the iron melting curve is unknown at conditions corresponding to planets of several times the Earth's mass (over 1500 GPa for planets with 10 times the Earth's mass (ME)). In the density-temperature region of the cores of those super-Earths, we calculate the iron melting curve using first principle molecular dynamics simulations based on density functional theory. By comparing this melting curve with the calculated thermal structure of Super Earths, we show that planets heavier than 2ME, have solid cores, thus precluding the existence of an internal metallic-core driven magnetic field. The iron melting curve obtained in this study exhibits a steeper slope than any calculated planetary adiabatic temperature profile rendering the presence of molten metallic cores less likely as sizes of terrestrial planets increase.