2019MNRAS.486.2570B

The observed discrete multiple stellar populations and internal abundance spreads in r- and s-process elements within globular clusters (GCs) have been suggested to be explained self-consistently by discrete star formation (SF) events over a longer time-scale (∼10⁸ yr). We here investigate whether such SF is really possible within GCs using numerical simulations that include effects of dynamical interaction between individual stars and the accumulated gas ('star-gas interaction') on SF. The principal results are as follows. Small gas clouds with densities larger than 10¹⁰ atoms cm^–3 corresponding to first stellar cores can be developed from gas without turbulence. Consequently, new stars can be formed from the gas with high star formation efficiencies (>0.5) in a bursty manner. However, SF can be suppressed when the gas mass fractions within GCs (f_g) are less than a threshold value (f_g,th). This f_g,th is larger for GCs with lower masses and larger gas discs. Star-gas interaction and gravitational potentials of GCs can combine to suppress the formation of massive stars (i.e. 'top-light' stellar initial mass function). Formation of He-rich stars directly from gas of massive asymptotic giant branch stars is possible in massive GCs due to low f_g,th (<0.01). Short bursty SF only for f_g > f_g,th can be partly responsible for discrete multiple SF events within GCs. We discuss how these results depend on the adopted model assumptions, such as rotating gas discs within GCs.