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The main accretion phase of star formation is investigated in clouds withdifferent metallicities in the range of 0 \le Z \le Z_\odot, resolving theprotostellar radius. Starting from a near-equilibrium prestellar cloud, wecalculate the cloud evolution up to \sim100 yr after the first protostarformation. The star formation process considerably differs between clouds withlower (Z \le 10^-4 Z_\odot) and higher (Z > 10^-4 Z_\odot) metallicities.Fragmentation frequently occurs and many protostars appear without forming astable circumstellar disc in lower-metallicity clouds. In these clouds,although protostars mutually interact and some are ejected from the cloudcentre, many remain as a small stellar cluster. In contrast, higher-metallicityclouds produce a single protostar surrounded by a nearly stablerotation-supported disc. In these clouds, although fragmentation occasionallyoccurs in the disc, the fragments migrate inwards and finally fall onto thecentral protostar. The difference in cloud evolution is due to differentthermal evolutions and mass accretion rates. The thermal evolution of the clouddetermines the emergence and lifetime of the first core. The first coredevelops prior to the protostar formation in higher-metallicity clouds, whereasno (obvious) first core appears in lower-metallicity clouds. The first coreevolves into a circumstellar disc with a spiral pattern, which effectivelytransfers the angular momentum outwards and suppresses frequent fragmentation.In lower-metallicity clouds, the higher mass accretion rate increases the discsurface density within a very short time, rendering the disc unstable toself-gravity and inducing vigorous fragmentation.

Accretion Phase of Star Formation in Clouds with Different Metallicities