Viswajith Vanaraj

Globular clusters have long been considered to be simple stellar populations. Recent research shows that they are multiple stellar populations (MSPs), in which the sub-populations differ in their abundance of light elements. One aspect of their enigmatic origins is to find out if they are influenced by their galactic environment. Since Red Giant Branch (RGB) is sensitive to light element abundance variations, we use RGB width to compare the globular clusters in Milkyway and Large Magellanic Clouds (LMC) to study the effect of galaxy environment in the formation of MSPs. We analyse two LMC clusters, namely NGC 1898 and NGC 1786, using HST archival data. Figure 1 explains the method to determine the observed RGB width and the subtraction of errors from it. We see that the observed RGB width correlates strongly with metallicity. After removing the effect of metallicity, we find that RGB width correlates strongly with mass. This shows that both metallicity and mass are required to explain the variance of RGB width. Figure 2 is a plot between total cluster mass and metallicity-subtracted RGB width. Since the two Large Magellanic Cloud clusters under analysis follow the same general trend as Mlikyway clusters, we conclude that galaxy environment may not play a role in the formation of MSPs.