دورية أكاديمية
The top-down solidification of iron asteroids driving dynamo evolution.
| العنوان: | The top-down solidification of iron asteroids driving dynamo evolution. |
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| المؤلفون: | Neufeld JA; BP Institute, University of Cambridge, Cambridge, UK.; Department of Earth Sciences, University of Cambridge, Bullard Laboratories, Cambridge, UK.; Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, UK., Bryson JFJ; Department of Earth Sciences, University of Cambridge, Bullard Laboratories, Cambridge, UK., Nimmo F; Department of Earth and Planetary Sciences, University of California, Santa Cruz, California, USA. |
| المصدر: | Journal of geophysical research. Planets [J Geophys Res Planets] 2019 May; Vol. 124 (5), pp. 1331-1356. |
| نوع المنشور: | Journal Article |
| اللغة: | English |
| بيانات الدورية: | Publisher: Wiley Subscription Services, Inc Country of Publication: United States NLM ID: 101661797 Publication Model: Print Cited Medium: Print ISSN: 2169-9097 (Print) Linking ISSN: 21699097 NLM ISO Abbreviation: J Geophys Res Planets Subsets: PubMed not MEDLINE |
| أسماء مطبوعة: | Original Publication: Hoboken, NJ : Wiley Subscription Services, Inc., 2013- |
| مستخلص: | The cores of some small planetesimals, such as asteroid (16) Psyche, are thought to have been exposed through collisions during the early solar system that removed their mantles. These small bodies likely solidified from the top down representing a fundamentally different solidification regime to that of Earth's core. Here we derive simplified models of the downwards solidification of the metallic crust, and consider thermal convection and the potential for viscous delamination of the weak, warm base of the crust to provide a buoyancy flux sufficient to drive a dynamo. Thermal buoyancy is very short lived (~1000 years), and therefore cannot be the source of measured paleomagnetic remanence. In contrast, viscous delamination is found to provide a long-lasting buoyancy flux sufficient to generate an intense, multipolar magnetic field, while not greatly affecting the crustal solidification time. Our results suggest that a Psyche-sized (150 km radius) body solidified in roughly 6.7 - 20 Myr, and that delamination produced a strong magnetic field over much of this time. Finally, including light, insoluble impurities, such as sulfur, results in a partially solid mushy zone at the base of the crust. This further weakens the base of the crust and results in smaller scale delamination events. Despite a significant change in the dynamics of delamination, the time to total solidification and the predicted properties of the magnetic field are broadly comparable to the sulfur-free case, though we argue this may result in observable compositional stratification of the body. |
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| معلومات مُعتمدة: | 80NSSC18K0601 United States ImNASA Intramural NASA |
| تواريخ الأحداث: | Date Created: 20200220 Latest Revision: 20210110 |
| رمز التحديث: | 20240628 |
| مُعرف محوري في PubMed: | PMC7027579 |
| DOI: | 10.1029/2018je005900 |
| PMID: | 32071828 |
| قاعدة البيانات: | MEDLINE |
Full Text Finder | تدمد: | 2169-9097 |
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| DOI: | 10.1029/2018je005900 |