Formation History of Binary Clusters in the Large Magellanic Cloud

Abstract

Global history of star or cluster formation in the Large Magellanic Cloud (LMC) has been the center of interest in several studies as it is thought to be influenced by tidal interaction with the Small Magellanic Cloud and even the Milky Way. This study focus on the formation history of the LMC in relation with the context of binary star clusters population, the apparent binary fraction (e.g., percentage of cluster pairs) in different epoch were calculated and analyzed. From the established distributions, it can be deduced that the binary clusters tend to be young (∽ 100 Myr) while their locations coincide with the locations of star forming complexes. There is an indication that the binary fraction increases as the rise of star formation rate in the last millions years. In the LMC, the increase of binary fraction at age ∽ 100 Myr can be associated to the last episode of close encounter with the Small Magellanic Cloud at ∽ 150 Myr ago. This observational evidence supports the theory of binary cluster formation through the fission of molecular cloud where the encounter between galaxies enhanced the clouds velocity dispersion which in turn increased the probability of cloud-cloud collisions that produce binary clusters.

The Formation of Binary Star Clusters in the Milky Way and Large Magellanic Cloud

“…The fraction reaches a maximum value of ∼ 90% at 𝑡 = 20 Myr and decrease to ∼ 80% at 𝑡 = 50 Myr. This suggests that the systems in the LMC environment can survive up to 100 Myr or even longer, as suggested by Priyatikanto et al (2019a). The fraction of merger products in the LMC higher: ∼ 3% − 10% at 𝑡 = 50 Myr.…”

“…The updated statistics of spatial properties, ages, sizes, and separation distributions from Priyatikanto et al (2019b) provide evidence that binary star cluster formation induced by cloud-cloud collisions through simultaneous or sequential mechanisms (de la Fuente Marcos & de la Fuente Marcos 2009); they identified 634 binary/multiple star cluster candidates in the LMC. According to Priyatikanto et al (2019a), the close encounter of the LMC with the Small Magellanic Cloud (SMC) roughly 150 Myr ago is one of the factors that has increased the formation rate of binary star clusters in the LMC.…”