When
3:30 p.m., Nov. 8, 2011
Where
Kuiper Space Sciences 308
Dr. Wayne Roberge
Rensselaer Polytechnic Institute
"Multifluid Shear Flows and Electrodynamic Heating of Primitive Solar System Bodies"
The discovery and recent confirmation of enantiomeric excesses in some extraterrestrial amino acids lends credence to a long-held notion, that chondritic meteorites were important sources of prebiotic molecules on Earth. The subject of this talk is the thermal history of chondrite parent bodies (CPBs), a crucial issue for understanding the prebiotic chemistry therein. Two mechanisms for heating asteroids have been studied extensively in the past: the decay of short-lived radionuclides and induction heating. However it has been pointed out by others that the age discrepancy between CAIs and chondrules poses difficulties for radioactive heating of the CPBs. I will demonstrate that classical induction heating is also ruled out because it is based on a subtle misconception. In the process of correcting this problem, we have discovered a related process which we call electrodynamic heating. Electrodynamic heating is physically correct, operates in weakly-ionized protoplanetary disks as well as fully-ionized plasmas, and predicts heating rates which are virtually identical to induction heating for a given set of physical conditions. The prospects for explaining CPB thermal histories in the context of electrodynamic heating will be discussed.
Rensselaer Polytechnic Institute
"Multifluid Shear Flows and Electrodynamic Heating of Primitive Solar System Bodies"
The discovery and recent confirmation of enantiomeric excesses in some extraterrestrial amino acids lends credence to a long-held notion, that chondritic meteorites were important sources of prebiotic molecules on Earth. The subject of this talk is the thermal history of chondrite parent bodies (CPBs), a crucial issue for understanding the prebiotic chemistry therein. Two mechanisms for heating asteroids have been studied extensively in the past: the decay of short-lived radionuclides and induction heating. However it has been pointed out by others that the age discrepancy between CAIs and chondrules poses difficulties for radioactive heating of the CPBs. I will demonstrate that classical induction heating is also ruled out because it is based on a subtle misconception. In the process of correcting this problem, we have discovered a related process which we call electrodynamic heating. Electrodynamic heating is physically correct, operates in weakly-ionized protoplanetary disks as well as fully-ionized plasmas, and predicts heating rates which are virtually identical to induction heating for a given set of physical conditions. The prospects for explaining CPB thermal histories in the context of electrodynamic heating will be discussed.