Multiple stellar population mass loss in massive Galactic globular clusters

Abstract

The degree of mass loss, that is the fraction of stars lost by globular clusters, and specifically by their different populations, is still poorly understood. Many scenarios of the formation of multiple stellar populations, especially the ones involving self-enrichment, assume that the first generation (FG) was more massive at birth than now in order to reproduce the current mass of the second generation (SG). This assumption implies that, during their long-term evolution, clusters lose around 90% of the FG. We tested whether such strong mass loss could take place in a massive globular cluster orbiting the Milky Way at 4 kpc from the centre that is composed of two generations. We performed a series of N-body simulations for 12 Gyr to probe the parameter space of internal cluster properties. We derive that, for an extended FG and a low-mass SG, the cluster loses almost 98% of its initial FG mass and the cluster mass can be as much as 20 times lower after a Hubble time. Furthermore, under these conditions, the derived fraction of SG stars, fenriched, falls in the range occupied by observed clusters of similar mass (∼0.6 − 0.8). In general, the parameters that affect the highest degree of mass loss are the presence or absence of primordial segregation, the depth of the central potential, W0, FG, the initial mass of the SG, MSGini, and the initial half-mass radius of the SG, rh, SG. Higher MSGini have not been found to imply higher final fenriched due to the deeper cluster potential well which slows down mass loss.

A JWST Project on 47 Tucanae. Overview, Photometry, and Early Spectroscopic Results of M Dwarfs and Observations of Brown Dwarfs*

“…2P stars are born from material processed and ejected by 1P stars (e.g., Cottrell & Da Costa 1981;Dantona et al 1983;Renzini et al 2022). Various kinds of 1P polluters have been proposed, including massive binary, asymptotic giant branch (AGB), rotating, and supermassive stars (e.g., Ventura et al 2001;Decressin et al 2007;de Mink et al 2009;Krause et al 2013;Denissenkov & Hartwick 2014;D'Antona et al 2016;Calura et al 2019;Lacchin et al 2024). However, regardless of proposed polluters, the amount of available material for 2P star formation is only a small fraction of the total present-day mass of 1P stars, a challenge known as the "mass budget problem."…”

“…In this context, it has been argued that GCs would have formed inside dwarf galaxies as a result of a cooling catastrophe, with a fraction of the dwarf itself having contributed material for the formation of 2Ps (Renzini et al 2022). As opposed to a compact, massive progenitor that would not lose much mass, a dense GC embedded in an extended envelope would easily survive tidal interaction while losing most of the envelope itself, e.g., as suggested by N-body simulations (Lacchin et al 2024).…”

A JWST Project on 47 Tucanae: NIRSpec Spectroscopy of Multiple Populations among M Dwarfs*

“…One way of achieving this has been recently proposed in which the host (dwarf) galaxy harbors extended star formation around the nascent GC, hence the original 1P stars are distributed over a much larger volume than the GC itself (Renzini et al 2022). Subsequent evolution and tidal interaction will then result in removing most of the original 1P stars, as indicated by N-body simulations (Lacchin et al 2024).…”