Richardton (meteorite)

from Wikipedia, the free encyclopedia

Richardton is as H5 chondrite classified meteorite . He fell on June 30, 1918 in North Dakota , USA. A total of 90 kg was recovered.

Richardton was in 1960 , a surplus of the first Xenon - Isotopes 129 detected Xe. This xenon isotope is created by the decay of the short-lived radionuclide 129 I and shows that this must have been present in the protoplanetary disk when the solar system was formed .
This was the first evidence for the existence of such short-lived radionuclides in the protoplanetary disk. Today many more radionuclides are known that existed then, such as 26 Al , 53 Mn , 60 Fe .

The existence of such radionuclides is important information if one wants to understand the processes in the protoplanetary disk. It is assumed that 26 Al and possibly also 60 Fe played a role as an energy source for the heating, which led to the melting and differentiation of asteroids . 60 Fe can probably only be produced in a supernova , so this is an indication that material from a supernova explosion, which must have taken place a very short time before the formation of the solar system, was released into the solar nebula from which the solar system was formed, was introduced. It is possible that the shock wave of this supernova explosion triggered the condensation of the solar nebula in the first place.

Many of these radionuclides are now used for the relative dating of material from the time the solar system was formed.
Richardton himself has been dated to 4.558 billion years using the I-Xe method, while the Mn- Cr age is 4.5563 billion years.
Since both methods are relative dating methods, they were calibrated using uranium-lead dating in order to be able to give absolute ages.
Direct dating using uranium-lead dating, which was carried out on phosphates from Richardton, gave an age of 4.5514 billion years.

These ages presumably do not date the original crystallization, but the later thermal metamorphosis of the asteroid from which Richardton originated. Since the uranium-lead isotope system terminates at lower temperatures than Mn-Cr or I-Xe, the difference in ages should reflect the slow cooling of this asteroid.

See also: List of meteorites