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arXiv 1102.4319astro-ph.GA
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星际彗星空间密度的一个上界

An Upper Bound to the Space Density of Interstellar Comets

M. Jura

摘要:

两颗被充分研究的白矮星都有氦占主导地位的大气层(DB),每颗白矮星的氢含量都比一颗平均质量的彗星少。很可能,这些恒星的风速足够低,以至于大多数吸积的氢都留在了恒星中。如果是这样的话,并假设它们的名义有效温度,那么这些DBs在其5000万年的冷却年龄期间受到星际彗星的影响最小;半径在10 m和2 km之间的星际冰球含有不到1%的星际氧气。这一分析表明,大多数恒星不会以奥尔特云形成的“乐观”情景所预测的速度产生彗星。

英文摘要:

Two well-studied white dwarfs with helium-dominated atmospheres (DBs) each possess less hydrogen than carried by a single average-mass comet. Plausibly, the wind rates from these stars are low enough that most accreted hydrogen remains with the star. If so, and presuming their nominal effective temperatures, then these DBs have been minimally impacted by interstellar comets during their 50 Myr cooling age; interstellar iceballs with radii between 10 m and 2 km contain less than 1% of all interstellar oxygen. This analysis suggests that most stars do not produce comets at the rate predicted by "optimistic" scenarios for the formation of the Oort cloud.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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