解开亚恒星磁层

IF 5.8 2区 物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS
Robert D. Kavanagh, Harish K. Vedantham, Kovi Rose, Sanne Bloot
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引用次数: 0

摘要

在亚恒星边界,磁场的特征开始以无线电波长显现,类似于磁化的太阳系行星的极光发射。这种辐射为在太阳系外行星尺度上测量磁场提供了一种独特的途径。到目前为止,系外行星还没有被无线电波长探测到。然而,超冷矮星(ucd),它们的高质量对应物,已经在无线电中被探测到20多年了。考虑到它们与大质量系外行星的相似特征,ucd是我们理解从恒星到行星磁场产生的理想目标。在这项工作中,我们开发了一种新的层析成像技术,用于从相干射电暴观测中反演ucd的视角和大尺度磁场结构。我们将我们的方法应用到附近的T8矮星WISE J062309.94-045624.6 (J0623)上,它最近在无线电波长上被探测到,并表明它可能是极点观测的。我们还发现J0623的旋转和磁轴明显错位,让人想起天王星和海王星,并表明它可能正在经历一个持续时间超过6个月的磁周期。这些发现表明,我们的方法是研究行星质量物体磁场的一个强大的新工具。随着下一代低频无线电设备的出现,本文提出的方法可以首次促进外行星磁层的表征。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Unravelling sub-stellar magnetospheres
At the sub-stellar boundary, signatures of magnetic fields begin to manifest at radio wavelengths, analogous to the auroral emission of the magnetised solar system planets. This emission provides a singular avenue for measuring magnetic fields at planetary scales in extrasolar systems. So far, exoplanets have eluded detection at radio wavelengths. However, ultracool dwarfs (UCDs), their higher mass counterparts, have been detected for over two decades in the radio. Given their similar characteristics to massive exoplanets, UCDs are ideal targets to bridge our understanding of magnetic field generation from stars to planets. In this work, we develop a new tomographic technique for inverting both the viewing angle and large-scale magnetic field structure of UCDs from observations of coherent radio bursts. We apply our methodology to the nearby T8 dwarf WISE J062309.94-045624.6 (J0623) which was recently detected at radio wavelengths, and show that it is likely viewed pole-on. We also find that J0623’s rotation and magnetic axes are misaligned significantly, reminiscent of Uranus and Neptune, and show that it may be undergoing a magnetic cycle with a period exceeding 6 months in duration. These findings demonstrate that our method is a robust new tool for studying magnetic fields on planetary-mass objects. With the advent of next-generation low-frequency radio facilities, the methods presented here could facilitate the characterisation of exoplanetary magnetospheres for the first time.
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来源期刊
Astronomy & Astrophysics
Astronomy & Astrophysics 地学天文-天文与天体物理
CiteScore
10.20
自引率
27.70%
发文量
2105
审稿时长
1-2 weeks
期刊介绍: Astronomy & Astrophysics is an international Journal that publishes papers on all aspects of astronomy and astrophysics (theoretical, observational, and instrumental) independently of the techniques used to obtain the results.
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