Training - PhD Theses

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Physical properties of large meteoroids in cometary orbits: dynamic clues on the cascade evolution of comets until becoming dormant NEOs

Status: proposal

Anual gross salary: 5000 Euros
Requisites
Degree in Physics or Enginnering, preferently with a master almost completed to continue with thesis preparation. Skills in programming languages: C++, Fortran and Matlab.
Description
Fred L. Whipple first modeled the formation of meteoroid streams from the continuous sublimation of the ice-rich regions in cometary nuclei. The usual formation model involves particles lifted off from ice-rich regions by the sublimated gas drag, probably biased towards fragile and fluffy aggregates. Many cometary meteoroid streams crossing the Earth were formed in this way, but not all. Catastrophic disruption of cometary nuclei is another mechanism of producing meteoroid streams. Interestingly, this mechanism is able to produce large boulders as observed e.g. during the disruption of comet C/1999 S4 LINEAR [8]. It was believed that the large fragments released during break-up events will proceed to faint into the coma due to suffer a cascade fragmentation. The resolution of telescopic observations is not able to decipher if the final product of these events are mm- or m-sized meteoroids. Several cometary streams can have m-sized meteoroids generated in cometary disruptions, being the Taurid complex associated with comet 2P/Encke among them. Several NEOs have been also identified as part of meteoroid complexes whose existence suggests their formation in catastrophic disruptions of comets in the remote past. The master thesis candidate will reduce fireball observations from the instruments operated by the SPanish Meteor and Fireball Network (www.spmn.uji.es; SPMN) so that measurements of its physical and dynamic properties will be obtained. I offer a 2013 full-year grant to be introduced in this field. The work made along the year will be compiled and published in a highly ranked peer-reviewed publication, and leaded by the hired researcher.