近日，美国哈佛大学的Jeremy Bloxham及其研究团队取得一项新进展。经过不懈努力，他们发现木星内部深处快速随时间变化的赤道喷流。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。

该研究团队证实喷流有一个周期约为4年的波状波动，强烈暗示了木星金属氢内部存在扭转振荡(一种围绕旋转轴的圆柱对称振荡流)或局部阿尔芬波。这为揭示金属氢区域内磁场的其他隐藏方面开辟了一条途径，从而限制了产生木星磁场的发电机效应。

据悉，行星磁场提供了一扇窗口，让人们得以了解行星内部深层的动力学。特别地，内部导电区域的流体流动与磁场之间的相互作用会引起外部观测到磁场的可观察长期变化(时间依赖性)。木星磁场的长期变化最近被揭示出来，并被证明部分是由轴对称的赤道喷流引起的。这种喷流是否与时间有关，以前还没有得到解决，但它对理解地球内部的动力学至关重要。如果稳定，它可能是深层发电机效应对流流动的表现(预计喷流是该流动的一部分)，但如果时间依赖于比几百年的对流周转时间短得多的时间尺度，它可能有不同的起源。

附：英文原文

Title: A rapidly time-varying equatorial jet in Jupiter’s deep interior

Author: Bloxham, Jeremy, Cao, Hao, Stevenson, David J., Connerney, John E. P., Bolton, Scott J.

Issue&Volume: 2024-03-06

Abstract: Planetary magnetic fields provide a window into the otherwise largely inaccessible dynamics of a planet’s deep interior. In particular, interaction between fluid flow in electrically conducting interior regions and the magnetic field there gives rise to observable secular variation (time dependency) of the externally observed magnetic field. Secular variation of Jupiter’s field has recently been revealed and been shown to arise, in part, from an axisymmetric, equatorial jet. Whether this jet is time dependent has not previously been addressed, yet it is of critical importance for understanding the dynamics of the planet’s interior. If steady, it would probably be a manifestation of deep dynamo convective flow (and jets are anticipated as part of that flow) but if time dependent on a timescale much shorter than the convective turnover timescale of several hundred years, it would probably have a different origin. Here we show that the jet has a wavelike fluctuation with a period of roughly 4years, strongly suggestive of the presence of a torsional oscillation (a cylindrically symmetric oscillating flow about the rotation axis) or a localized Alfvén wave in Jupiter’s metallic hydrogen interior. This opens a pathway towards revealing otherwise hidden aspects of the magnetic field within the metallic hydrogen region and hence constraining the dynamo that generates Jupiter’s magnetic field.

DOI: 10.1038/s41586-024-07046-3

Source: https://www.nature.com/articles/s41586-024-07046-3