A new scenario for the formation of globular clusters and their peculiarities

Globular clusters in galaxies still challenge astronomers to find a satisfactory explanation for a number of their properties, namely: (i) their very formation: (ii) the origin of their heavy elements; (iii) the trend of their metallicity with distance from the centre of the parent galaxy; (iv) the apparent correlation of their average metallicity with the mass of the galaxy with which they are associated: and, (v) the need of a 'second parameter' (age, helium, [CNO/Fe] perhaps) to explain the variety of morphologies of their colour-magnitude diagrams. (Auth.)