2025ApJ...986..139P

Galactic globular clusters consist of two main stellar populations, the pristine (1P) and polluted (2P) stars. The fraction of 1P stars in clusters, F_1P, is a decreasing function of the present-day cluster mass, m_prst. The information about cluster formation it contains has yet to be unlocked. Paper I demonstrated that the observed distribution (m_prst, F_1P) of Galactic globular clusters can result from a pristine-star fraction that is inversely proportional to their birth mass, m_ecl. This relation was then calibrated with a fixed stellar mass threshold for 2P-star formation, m_th, i.e., F_1P = m_th/m_ecl. We now estimate the masses m_init of Galactic globular clusters as they start their long-term gas-free evolution in the Galaxy and we map their behavior in the (m_init, F_1P) space. Several dissolution timescales are tested (with and without primordial mass segregation), each yielding its own initial cluster distribution (m_init, F_1P). The (m_init, F_1P) distributions are mapped according to cluster origin, with the emphasis on the Disk, Low-Energy and Gaia-Enceladus cluster groups of D. Massari et al. All three initial distributions (m_init, F_1P) are more compact than their present-day counterparts since dynamical evolution scatters clusters in the F_1P versus cluster-mass space. The Disk initial distribution is the tightest one and potential reasons for this are discussed. Its power-law representation allows us to generalize the initial mass threshold of Paper and prompts us to represent the cluster (mass, F_1P) distribution in a log-log space. No evidence is found suggesting that, initially, the pristine-star fraction of globular clusters depends on their metallicity on top of their mass.