S316p.84 — The Initial Mass Function of Young Open Clusters in the Galaxy: A Preliminary Result

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Beomdu Lim1, Hwankyung Sung2, Hyeonoh Hur2, Byeong-Gon Park1

Institution(s): 1. Korea Astronomy and Space Science Institute, 2. Sejong University

Since the stellar mass is the final product of the star formation processes, the formation mechanisms are imprinted in the mass distribution of stars. The initial mass function (IMF) is, therefore, an essential tool to study star formation processes. Young open clusters in the Galaxy are ideal laboratories to study star formation processes because the members are not only coeval but also co-spatial population. We have initiated the photometric survey of young open clusters in the Galaxy, from which the stellar IMFs are obtained in a homogeneous way. A total of 13 famous young open clusters have preferentially been studied up to now. These clusters have a wide range of surface densities (log σ = -1 — 3 [stars pc-2] for stars with mass larger than 5 M) and total masses (MTotal = 500 — 50000 M) and also are distributed in five different spiral arms in the Galaxy. It is possible to test the dependence of star formation processes on the global properties of individual clusters or the environmental conditions. According to our preliminary result, the slope (the power law index Γ) of the IMFs in the high-mass regime appears to be shallow for massive compact clusters. The mass of the most massive star in a given cluster also has a tendency to be large in massive clusters. In addition, young open clusters particularly in the Perseus spiral arm seem to show a large scatter in the slope of the IMFs although the number of our samples is not sufficiently large enough to draw any firm conclusion. Tentatively, we suggest that the star formation is unlikely to be controlled by the universal processes.