Training - PhD Theses

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Photometric follow-up of potentially hazardous asteroids: physical evolution and surface properties from meteorites.

Status: proposal

University: Universitat Autònoma de Barcelona
Anual gross salary: 26000 Euros
Requisites

Degree in Physics, Chemistry, Geology or Enginnering, preferently with a master almost completed to continue with thesis preparation. Skills in stellar photometry (e.g. IRAF) programming languages: C++, Fortran and Matlab.

Description

Most km-sized near-Earth objects (NEOs) have been already discovered by current NEO telescopic surveys. We have already set up a new follow-up program using the 0.8m in diameter Joan Oró robotic telescope at OAdM. We plan to follow Potentially Hazardous Asteroids (PHAs) and obtain remote reflectance spectra to be compared with the laboratory spectra of meteorites. We will also analyze the possible flux of tens of meters in size asteroids by using SPMN video imagery (www.spmn.uji.es). Most of these  bodies have low albedos and eccentric orbits that make them tough targets to be discovered by current ground-based surveys so the Ph.D. work will try to obtain answers on the natural processes that contribute to surface darkening. It is found that these small NEOs are preferentially disrupted in the atmosphere. Such catastrophic events are called airbursts or airblasts and release significant energy in the stratosphere to generate dangerous shock waves that might propagate a significant part of the blast energy into the ground.  Consequently, these events are still dangerous for human beings and need to be considered when discussing about impact hazard. The largest airburst known in modern age is the famous Tunguska event occurred on June 30, 1908 over a remote Siberia region that produced the destruction of 2,150 km^2 of Siberian forest. Another unexpected superbolide event with a peak brightness equivalent to an absolute magnitude of -28 and a released energy over 500 ktons of TNT occurred on Feb. 15th, 2013 over Chelyabinsk in Russia. Most of these catastrophic events passed unnoticed in the past, but now that infrasound and satellite detectors can detect airbursts worlwide are perfectly detectable. It is found that the number of such events is larger than expected for that rangeof size from the extrapolation of large NEO encounters. Several physical processes are behind that enhanced number of asteroid/cometary fragments. We will study the importance of studying NEO approaches, to better quantify the impact hazard, and also the relevance of studying meteorites to better assess the intrinsic hazard behind future NEO encounters. The candidate will incorporate into the Meteorite, Minor Bodies and Planetary Science research group at ICE.