arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2412.01409astro-ph.EP
收藏

一种无撞击的类地行星及系外行星送水机制

An impact-free mechanism to deliver water to terrestrial planets and exoplanets

Quentin Kral, Paul Huet, Camille Bergez-Casalou, Philippe Thébault, Sébastien Charnoz, Sonia Fornasier

AI总结:

本文提出一种无需撞击的类地行星及系外行星送水机制,通过原始小行星冰升华形成气态盘输送水,模型解释了地球及其他行星含水量,且该机制可通过ALMA探测,比撞击场景更普遍。

摘要:

迄今为止,最普遍的场景是地球形成时没有水,水主要是由来自太空更远处的含水小行星撞击带来的。然而,关于向内太阳系类地行星供水的确切过程仍存在许多不确定性。本文探讨了一种无需撞击即可高效向行星输送水的新机制。我们提出,原始小行星是 icy 的,当冰升华时,会形成一个气态盘,该盘随后可到达行星并输送水。我们开发了一个新模型,该模型跟踪小行星的升华过程,并使用粘性扩散代码演化后续的气体盘。然后,我们可以以自洽的方式量化每个行星可吸积的水量。我们发现,这种新的盘输送机制可以解释地球以及其他行星的含水量。我们的模型显示,大部分水是在太阳诞生后 20 至 30 Myr 之间输送的。我们的场景意味着存在一个质量可观的气态水盘,持续时间达 100s Myr,这可能是该机制的关键示踪物之一。我们表明,这种水盘可以用 ALMA 在年轻的系外小行星带中探测到。我们提出,粘性水输送是不可避免的,且比撞击场景更具普遍性。我们还认为,这是一个普遍过程,可能也发生在系外行星系统中。该场景展开所需的条件确实有望存在于大多数行星系统中:一个不透明的原行星盘,其初始温度足够低,可在系外小行星带区域形成冰;随后,雪线自然向外移动,使原始盘消散后初始冰升华,形成粘性的次级气体盘,导致水吸积到系外行星上。

英文摘要:

To date, the most widespread scenario is that the Earth originated without water and was brought to the planet mainly due to impacts by wet asteroids coming from further out in space. However, many uncertainties remain regarding the exact processes that supply water to inner terrestrial planets. This article explores a new mechanism that would allow water to be efficiently transported to planets without impacts. We propose that primordial asteroids were icy and that when the ice sublimated, it formed a gaseous disk that could then reach planets and deliver water. We have developed a new model that follows the sublimation of asteroids and evolves the subsequent gas disk using a viscous diffusion code. We can then quantify the amount of water that can be accreted onto each planet in a self-consistent manner. We find that this new disk-delivery mechanism can explain the water content on Earth as well as on other planets. Our model shows most of the water being delivered between 20 and 30 Myr after the birth of the Sun. Our scenario implies the presence of a gaseous water disk with substantial mass for 100s Myr, which could be one of the key tracers of this mechanism. We show that such a watery disk could be detected in young exo-asteroid belts with ALMA. We propose that viscous water transport is inevitable and more generic than the impact scenario. We also suggest it is a universal process that may also occur in extrasolar systems. The conditions required for this scenario to unfold are indeed expected to be present in most planetary systems: an opaque proto-planetary disk that is initially cold enough for ice to form in the exo-asteroid belt region, followed by a natural outward-moving snow line that allows this initial ice to sublimate after the dissipation of the primordial disk, creating a viscous secondary gas disk and leading to the accretion of water onto the exoplanets.

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。

↑