ﻻ يوجد ملخص باللغة العربية
Galactic globular cluster (GC) stars exhibit abundance patterns which are not shared by their field counterparts, In the framework of the widely accepted self-enrichment scenario for GCs, we present a new method to derive the Initial Mass Function (IMF) of the polluter stars, by using the observed O/Na abundance distribution. We focus on NGC 2808, a GC for which the largest sample of O and Na abundance determinations is presently available. We consider two classes of possible culprits : massive Asymptotic Giant Branch (AGB) stars (4-9 Msun) and winds of massive stars (WMS) in the mass range 10-100 Msun. We obtain upper limits for the slope of the IMF (assumed to be given by a power-law) of the stars initially more massive than the present turnoff mass. We also derive lower limits for the amount of stellar residues. We find that the polluter IMF had to be much flatter than presently observed IMFs in stellar clusters, in agreement with the results of two other methods for GC IMF determination. Additionaly, we find that the present mass of the GC should be totally dominated by stellar remnants if the polluters were AGB stars, but not so in the case of WMS. We critically analyse the advantages and shortcomings of each potential polluter class, and we find the WMS scenario more attractive.
Recently, high-dispersion spectroscopy has demonstrated conclusively that four of the five globular clusters (GCs) in the Fornax dwarf spheroidal galaxy are very metal-poor with [Fe/H]<-2. The remaining cluster, Fornax 4, has [Fe/H]=-1.4. This is in
A significant fraction of stars in globular clusters (about 70%-85%) exhibit peculiar chemical patterns with strong abundance variations in light elements along with constant abundances in heavy elements. These abundance anomalies can be created in t
By means of analytical calculations, we explore the self-enrichment scenario for Globular Cluster formation. According to this scenario, an initial burst of star formation occurs inside the core radius of the initial gaseous distribution. The outward
We analyze in detail various possible sources of systematic errors on the distances of globular clusters derived by fitting a local template DA white dwarf sequence to the cluster counterpart (the so-called WD-fitting technique). We find that the unk
We investigate the colour-magnitude relation of metal-poor globular clusters, the blue tilt, in the Hydra and Centaurus galaxy clusters and constrain the primordial conditions for star cluster self-enrichment. We analyse U,I photometry for about 2500