Primeval Galaxies

Actually, we are interested in reaching a behaviour in which no trend exist anymore with metallicity, situation expected if the polluting SNe are primordial, i.e. without elements heavier than lithium. From our diagrams such a regime seems to hold for [Mg/H] < -2.9. We then consider the mean of the [X/Mg] ratios for [Mg/H] < -2.9 as representative of the yields in the primeval Galaxy. They are given in table 1. 

Abstract. We present early results of a near-in ared search for Primeval Galaxies (PGs), i.e., galaxies forming the bulk of their stars at high reddiift. These results are compart with some theoretical expectations on the surface density of the PGs. 

An unknown event disturbed the equilibrium of the interstellar cloud, and it collapsed. This process may have been caused by shock waves from a supernova explosion, or by a density wave of a spiral arm of the galaxy. The gas molecules and the particles were compressed, and with increasing compression, both temperature and pressure increased. It is possible that the centrifugal forces due to the rotation of the system prevented a spherical contraction. The result was a relatively flat, rotating disc of matter, in the centre of which was the primeval sun. Analogues of the early solar system, i.e., protoplanetary discs, have been identified from the radiation emitted by T Tauri stars (Koerner, 1997). 

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