Failed supernova explosions increase the duration of star formation in globular clusters

¹ Charles University, Faculty of Mathematics and Physics, Astronomical Institute, V Holešovičkách 2, Praha 18000, Czech Republic
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
³ School of Astronomy and Space Science, Nanjing University, Nanjing 210023, China
⁴ Helmholtz Institut für Strahlen und Kernphysik, Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany

^★ Corresponding author; wirth@sirrah.troja.mff.cuni.cz

Received: 22 June 2024
Accepted: 9 October 2024

Abstract

Context. The duration of star formation (SF) in globular clusters (GCs) is an essential aspect for understanding their formation. Contrary to previous presumptions that all stars above 8 M_⊙ explode as core-collapse supernovae (CCSNe), recent evidence suggests a more complex scenario.

Aims. We analyse iron spread observations from 55 GCs to estimate the number of CCSNe explosions before SF termination, thereby determining the SF duration. This work for the first time takes the possibility of failed CCSNe into account, when estimating the SF duration.

Methods. Two scenarios are considered: one where all stars explode as CCSNe and another where only stars below 20 M_⊙ lead to CCSNe, as most CCSN models predict that no failed CCSNe happen below 20 M_⊙ .

Results. This establishes a lower (≈3.5 Myr) and an upper (≈10.5 Myr) limit for the duration of SF. Extending the findings of our previous paper, this study indicates a significant difference in SF duration based on CCSN outcomes, with failed CCSNe extending SF by up to a factor of three. Additionally, a new code is introduced to compute the SF duration for a given CCSN model.

Conclusions. The extended SF has important implications on GC formation, including enhanced pollution from stellar winds and increased binary star encounters. These results underscore the need for a refined understanding of CCSNe in estimating SF durations and the formation of multiple stellar populations in GCs.