近日，英国华威大学的Antoine Bédard与加拿大维多利亚大学的Simon Blouin以及美国普林斯顿高等研究院的Sihao Cheng合作并取得一项新进展。经过不懈努力，他们发现浮力晶体阻止白矮星的冷却。相关研究成果已于2024年3月6日在国际权威学术期刊《自然》上发表。

该研究团队表明蒸馏中断了数十亿年的冷却，并解释了不寻常延迟星系族的所有观测特性。这些白矮星的亮度稳定，超过了一些主序星，它们打破了传统的死亡恒星形象。这一研究结果强调了特殊合并残留物的存在，并对使用白矮星来确定恒星族的年代具有深远的意义。

据悉，白矮星是没有核能的恒星残骸，在数十亿年的时间里逐渐冷却，最终由内而外冻结成固态。最近，人们发现，一些冰冻的白矮星在与宇宙年龄相当的时间内保持着恒定的亮度，这表明存在一种强大但未知的能量来源，可以抑制冷却。对于某些核心成分，由于固相在重杂质中被耗尽，预计冻结过程将触发固液蒸馏机制。这样形成的晶体具有浮力并向上漂浮，从而将较重的液体向下置换并释放引力能。

附：英文原文

Title: Buoyant crystals halt the cooling of white dwarf stars

Author: Bedard, Antoine, Blouin, Simon, Cheng, Sihao

Issue&Volume: 2024-03-06

Abstract: White dwarfs are stellar remnants devoid of a nuclear energy source, gradually cooling over billions of years and eventually freezing into a solid state from the inside out. Recently, it was discovered that a population of freezing white dwarfs maintains a constant luminosity for a duration comparable with the age of the universe, signalling the presence of a powerful, yet unknown, energy source that inhibits the cooling. For certain core compositions, the freezing process is predicted to trigger a solid–liquid distillation mechanism, owing to the solid phase being depleted in heavy impurities. The crystals thus formed are buoyant and float up, thereby displacing heavier liquid downward and releasing gravitational energy. Here we show that distillation interrupts the cooling for billions of years and explains all the observational properties of the unusual delayed population. With a steady luminosity surpassing that of some main-sequence stars, these white dwarfs defy their conventional portrayal as dead stars. Our results highlight the existence of peculiar merger remnants and have profound implications for the use of white dwarfs in dating stellar populations.

DOI: 10.1038/s41586-024-07102-y

Source: https://www.nature.com/articles/s41586-024-07102-y