Types of Presolar Material
Presolar grains consisting of the following minerals have so far been identified:
- diamond (C) nanometer-sized grains (~ 2.6 nm diameter) possibly formed by vapor deposition
- graphite (C) particles and onions, some with unlayered graphene cores
- silicon carbide (SiC) submicrometer to micrometer sized grains. Presolar SiC occurs as single-polytype grains or polytype intergrowths. The atomic structures observed contain the two lowest order polytypes: hexagonal 2H and cubic 3C (with varying degrees of stacking fault disorder) as well as 1-dimensionally disordered SiC grains. In comparison, terrestrial laboratory synthesized SiC is known to form over a hundred different polytypes.
- titanium carbide (TiC) and other carbides within C and SiC grains
- silicon nitride (Si3N4)
- corundum (Al2O3)
- spinel (MgAl2O4)
- hibonite ((Ca,Ce)(Al,Ti,Mg)12O19)
- titanium oxide (TiO2)
- silicate minerals (olivine and pyroxene)
Read more about this topic: Presolar Grains
Famous quotes containing the words types of, types and/or material:
“... there are two types of happiness and I have chosen that of the murderers. For I am happy. There was a time when I thought I had reached the limit of distress. Beyond that limit, there is a sterile and magnificent happiness.”
—Albert Camus (1913–1960)
“The bourgeoisie loves so-called “positive” types and novels with happy endings since they lull one into thinking that it is fine to simultaneously acquire capital and maintain one’s innocence, to be a beast and still be happy.”
—Anton Pavlovich Chekhov (1860–1904)
“Decisive inventions and discoveries always are initiated by an intellectual or moral stimulus as their actual motivating force, but, usually, the final impetus to human action is given by material impulses ... merchants stood as a driving force behind the heroes of the age of discovery; this first heroic impulse to conquer the world emanated from very mortal forces—in the beginning, there was spice.”
—Stefan Zweig (18811942)