标题： 古老行星系统围绕着大量白矮星运行 显示英文标题

标题： Ancient planetary systems are orbiting a large fraction of white dwarf stars

摘要： 红外研究揭示了在约30%的年轻、中等质量、主序星周围可能存在与行星形成相关的碎片。 我们基于各种比氦重的元素对大气的污染，提供了证据，表明这类主序星的白矮星后代中，有相当比例被行星系统环绕。 这些系统至少部分地经历了白矮星形成之前的全部恒星演化阶段。 在典型的污染白矮星样本中，其冷却时间约为2亿年，在这段时间内，它从其行星系统中吸积了相当于我们太阳系中最大小行星（例如灶神星或谷神星）的质量。 通常，这种吸积的质量只是围绕这些白矮星的岩石物质总质量的一小部分；对于合理的行星系统配置，我们估计这一总质量很可能至少等于太阳系的小行星带质量，甚至可能更大。 我们报告了在研究较少的恒星G241-6中检测到的一套8种元素的丰度，我们发现该恒星是所有中等亮度白矮星中最受污染的之一。 显示英文摘要

摘要： Infrared studies have revealed debris likely related to planet formation in orbit around ~30% of youthful, intermediate mass, main sequence stars. We present evidence, based on atmospheric pollution by various elements heavier than helium, that a comparable fraction of the white dwarf descendants of such main sequence stars are orbited by planetary systems. These systems have survived, at least in part, through all stages of stellar evolution that precede the white dwarf. During the time interval (~200 million years) that a typical polluted white dwarf in our sample has been cooling it has accreted from its planetary system the mass of one of the largest asteroids in our solar system (e.g., Vesta or Ceres). Usually, this accreted mass will be only a fraction of the total mass of rocky material that orbits these white dwarfs; for plausible planetary system configurations we estimate that this total mass is likely to be at least equal to that of the Sun's asteroid belt, and perhaps much larger. We report abundances of a suite of 8 elements detected in the little studied star G241-6 that we find to be among the most heavily polluted of all moderately bright white dwarfs.