# Star formation within globular clusters:discrete multiple bursts and top-light mass functions

## TL;DR

This study uses numerical simulations to explore how discrete star formation events and top-light initial mass functions can occur within globular clusters, influenced by gas dynamics and cluster mass.

## Contribution

It demonstrates that star formation in GCs can be bursty and suppressed based on gas fraction thresholds, and explains the formation of multiple stellar populations.

## Key findings

- High star formation efficiency (>0.5) in bursty events from dense gas clouds.
- Star formation suppression occurs below a gas fraction threshold, varying with cluster mass.
- Formation of He-rich stars from AGB star gas is possible in massive GCs.

## Abstract

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 events over a longer timescale (10^8 yr). We here investigate whether such star formation 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 star formation. The principal results are as follows. Small gas clouds with densities larger than $10^{10}$ 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, star formation 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 disks. 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 AGB stars is possible in massive GCs due to low f_g, th (<0.01). Short bursty star formation only for f_g>f_g, th can be partly responsible for discrete multiple star formation events within GCs.