论文标题
白矮人揭示的系外行星的快速形成
Rapid Formation of Exoplanetesimals Revealed by White Dwarfs
论文作者
论文摘要
第一个行星的形成时间确定了行星积聚的模式以及它们的地球物理和成分进化。间接盘和太阳系的天文观察结果为分子云塌陷期间的行星形成提供了证据，比先前估计的要早得多。在这里，我们提出了来自白矮星行系统的明显观察证据，用于在云层系统中云倒塌后的头几十万年内发生的行星形成。大量的白色矮人的一小部分具有富含铁芯或地幔材料的行星材料。为了使白矮人积聚的exo-asteroids形成铁芯，需要大量加热。通过模拟行星的进化和碰撞进化，我们表明，最可能的热源是短寿命的放射性核素，例如Al-2（一半寿命约为0.7 Myr）。因此，白矮人大气中的核心材料富含核心的材料为快速行星形成提供了独立的证据，并与恒星形成同时。
The timing of formation for the first planetesimals determines the mode of planetary accretion and their geophysical and compositional evolution. Astronomical observations of circumstellar discs and Solar System geochronology provide evidence for planetesimal formation during molecular cloud collapse, much earlier than previously estimated. Here, we present distinct observational evidence from white dwarf planetary systems for planetesimal formation occurring during the first few hundred thousand years after cloud collapse in exoplanetary systems. A significant fraction of white dwarfs have accreted planetary material rich in iron core or mantle material. In order for the exo-asteroids accreted by white dwarfs to form iron cores, substantial heating is required. By simulating planetesimal evolution and collisional evolution we show that the most likely heat source is short-lived radioactive nuclides such as Al-2 (half life of approximately 0.7 Myr). Core-rich materials in the atmospheres of white dwarfs, therefore, provide independent evidence for rapid planetesimal formation, concurrent with star formation.
