“…Moreover, such inequivalences may survive at the thermodynamic limit if forces are long ranged as for self gravitating objects [3,4]. In fact the characteristic of phase transitions in finite systems, and in particular the occurrence of a negative heat capacity, have first been discussed in the astrophysical context [2,31,26,69,70,71,72,73]. Since these pioneering works in astrophysics, an abundant literature is focused on the understanding of phase transition in small systems from a general point of view [15,30,36,74,75,76,77,78,79] or in the mean-field context [4,80] or for some specific systems such as metallic clusters [48,68] or nuclei [81] and even DNA [82].…”