Are exoplanetesimals differentiated?

Metals observed in the atmospheres of white dwarfs suggest that many have recently accreted planetary bodies. In some cases, the compositions observed suggest the accretion of...在白矮星大气中观测到的金属元素表明，多数白矮星近期曾吸积过行星天体。部分案例中，观测得到的元素组成暗示其曾吸积……