The origin of meteorites: Collisional evolution of chondritic parent objects

PARISI, M. GABRIELA; E. BEITZ(*); J. BLUM(*); (*) TECHNISCHE UNIVERSITAT BRAUNSCHWEIG, INSTITUT FUR GEOPHYSIK UND ETECHNISCHE UNIVERSITAT

La Plata

Congreso; CRAAA, VOL58; 2015

Asociación Argentina de Astronomía

Among meteorites, chondrites represent the 86 % ofthe  falls, 80 %  of these  being the  so-called ordinarychondrites  (OCs),  while 6 %  are  called  carbonaceouschondrites  (CCs).  Meteorites  are probably  fragments  from recent collisions in  the Asteroid Belt  (AB). Porosity (the  percentage of pore  space  within the  object)  is  a  particular useful  physical property,  as it  depends solely  on the  structure and  not  on the mineral composition of the  meteorite. The present mean impact speed in the AB is in the range  3.3 - 5 km/s. At such high speeds,  catastrophic  collisions among  small  asteroids occur  on few  Myrs  resulting  in  disruption of  the  bodies  in  several fragments  of  constant mass  density.  However,  the volume filling  factor  (defined  as  1-porosity) for  CCs  cover  a  range $phi$=0.58  and  $phi$=1 with a mean value  of 0.8. To explain this porosity a  dynamically  cold AB  would be  required in  contrast with  the well  known dynamically hot AB. We propose an scenario in which the origin  of the present flux of chondrites is the interior of large asteroids  with primordial radius between 35 and  268 km.