论文标题
热 - 新闻沙漠中的残余行星核心
A remnant planetary core in the hot-Neptune desert
论文作者
论文摘要
巨型行星的内部仍然很少了解。即使对于太阳系中的行星，观察的困难也会导致行星岩心的性质不确定性。经历了罕见进化过程的系外行星为理解行星内部的途径提供了途径。事实证明，在通常的贫瘠的热北部“沙漠”（Mass-Radius空间中的一个区域）中发现的行星已被证明在这方面特别有价值。这些行星包括HD149026B，被认为具有异常庞大的核心，以及最近发现的LTT9779B和NGTS-4B，在该发现上，光蒸发在其上消除了其外部大气的很大一部分。 Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune's but an anomalously large mass of $39.1^{+2.7}_{-2.6}$ Earth masses and a density of $5.2^{+0.7}_{-0.8}$ grams per cubic centimetre, similar to Earth's.内部结构模型表明，任何纯氢和氦气的气态包膜都由不超过$ 3.9^{+0.8} _ { - 0.9} $的总行星质量组成。该行星本来可以是一个天然气巨人，然后通过热自distrup乱或巨型行星碰撞遭受极大的质量损失，或者它可以通过间隙开口或迟到地层来避免大量的气体积聚。尽管光蒸发率无法说明减少木星样气体巨头所需的质量损失，但它们可以在数十亿年的时间尺度上去除一个小的（几个地球质量）氢和氦信封，这意味着TOI-849b上的任何剩余大气都可能被水或其他挥发物从星球室内室内富含。我们得出的结论是，TOI-849b是一个巨大星球的残余核心。
The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Planets found in and near the typically barren hot-Neptune 'desert' (a region in mass-radius space that contains few planets) have proved to be particularly valuable in this regard. These planets include HD149026b, which is thought to have an unusually massive core, and recent discoveries such as LTT9779b and NGTS-4b, on which photoevaporation has removed a substantial part of their outer atmospheres. Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune's but an anomalously large mass of $39.1^{+2.7}_{-2.6}$ Earth masses and a density of $5.2^{+0.7}_{-0.8}$ grams per cubic centimetre, similar to Earth's. Interior structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than $3.9^{+0.8}_{-0.9}$ per cent of the total planetary mass. The planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it could have avoided substantial gas accretion, perhaps through gap opening or late formation. Although photoevaporation rates cannot account for the mass loss required to reduce a Jupiter-like gas giant, they can remove a small (a few Earth masses) hydrogen and helium envelope on timescales of several billion years, implying that any remaining atmosphere on TOI-849b is likely to be enriched by water or other volatiles from the planetary interior. We conclude that TOI-849b is the remnant core of a giant planet.
