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Weak Magnetic Fields in the Outer Solar Nebula Recorded in CR Chondrites
Journal of Geophysical Research: Planets ( IF 4.8 ) Pub Date : 2020-05-08 , DOI: 10.1029/2019je006260
Roger R. Fu 1 , Pauli Kehayias 1, 2 , Benjamin P. Weiss 3 , Devin L. Schrader 4 , Xue‐Ning Bai 5 , Jacob B. Simon 6, 7, 8
Affiliation  

Theoretical investigations suggest that magnetic fields may have played an important role in driving rapid stellar accretion rates and efficient planet formation in protoplanetary disks. Experimental constraints on magnetic field strengths throughout the solar nebula can test the occurrence of magnetically driven disk accretion and the effect of magnetic fields on planetary accretion. Here we conduct paleomagnetic experiments on chondrule samples from primitive CR (Renazzo type) chondrites GRA 95229 and LAP 02342, which likely originated in the outer solar system between 3 and 7 AU approximately 3.7 million years after calcium aluminum‐rich inclusion formation. By extracting and analyzing 18 chondrule subsamples that contain primary, igneous ferromagnetic minerals, we show that CR chondrules carry internally non‐unidirectional magnetization that requires formation in a nebular magnetic field of ≤8.0 ± 4.3 μT (2σ). These weak magnetic fields may be due to the secular decay of nebular magnetic fields by 3.7 million years after calcium aluminum‐rich inclusions, spatial heterogeneities in the nebular magnetic field, or a combination of both effects. The possible inferred existence of spatial variations in the nebular magnetic field would be consistent with a prominent role for disk magnetism in the formation of density structures leading to gaps and planet formation.

中文翻译:

CR球粒陨石记录的太阳外星云中的弱磁场

理论研究表明,磁场可能在驱动快速恒星增长速率和原行星盘中有效行星形成方面发挥了重要作用。整个太阳星云上磁场强度的实验约束条件可以测试磁驱动磁盘积聚的发生以及磁场对行星积聚的影响。在这里,我们对原始CR(Renazzo型)球粒陨石GRA 95229和LAP 02342的球粒样品进行古磁实验,它们可能起源于3到7 AU之间的外部太阳系,大约在富铝钙钙包裹体形成后370万年。通过提取和分析18种含有原生火成铁磁性矿物的软骨子样品,σ)。这些弱磁场可能是由于富含钙铝的夹杂物引起的370万年后,神经元磁场的长期衰变,神经元磁场中的空间异质性或两者兼而有之。可能推断出的星云磁场中空间变化的存在与磁盘磁场在导致间隙和行星形成的密度结构的形成中的显着作用相一致。
更新日期:2020-05-08
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