Long-lived magnetism from solidification-driven convection on the pallasite parent body.

Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven, implying that magnetic activity would have been short-lived. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core is consistent with our measured magnetic field characteristics and cooling rates. Solidification-driven convection was probably common among small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar System.The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement No. 320750, the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 312284, the Natural Environment Research Council, Fundación ARAID and the Spanish MINECO MAT2011-23791.This is the accepted manuscript. The final version is available from Nature at http://www.nature.com/nature/journal/v517/n7535/full/nature14114.html

Long-lived magnetism from solidification-driven convection on the pallasite parent body

This is the accepted manuscript. The final version is available from Nature at http://www.nature.com/nature/journal/v517/n7535/full/nature14114.html.Paleomagnetic measurements of meteorites suggest that, shortly after the birth of the\ud solar system, the molten metallic cores of many small planetary bodies convected\ud vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven, implying that magnetic activity would\ud have been short-lived. Here we present a time-series paleomagnetic record of the field\ud recorded by the Imilac and Esquel pallasite meteorites, derived from nanomagnetic\ud images of their metallic matrices. The results reveal a history of long-lived magnetic\ud activity on the pallasite parent body, capturing the decay and eventual shut down of the\ud magnetic field. We demonstrate that magnetic activity driven by progressive solidification\ud of an inner core is consistent with our measured magnetic field characteristics and\ud cooling rates. Solidification-driven convection was likely common among small body\ud cores, and, in contrast to thermally driven convection, will have led to a relatively late\ud (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early solar system.The research leading to these\ud results has received funding from the European Research Council under the European Union's\ud Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement No. 320750, the\ud European Community's Seventh Framework Programme (FP7/2007-2013) under grant\ud agreement no. 312284, the Natural Environment Research Council, Fundaci?n ARAID and the\ud Spanish MINECO MAT2011-23791

Long-lived magnetism from solidification-driven convection on the pallasite parent body

Letter.-- et al.Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven, implying that magnetic activity would have been short-lived. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging10 of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core is consistent with our measured magnetic field characteristics and cooling rates. Solidification-driven convection was probably common among small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar SystemThe research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC grant agreement numbers 320750 and 312284, the Natural Environment Research Council, Fundación ARAID and the Spanish MINECO MAT2011-23791.Peer reviewe

Long-lived magnetism from solidification-driven convection on the pallasite parent body

Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven implying that magnetic activity would have been short-lived. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging10 of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core11, is consistent with our measured magnetic field characteristics and cooling rates. Solidification-driven convection was probably common among small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar System