The binary fraction of the young cluster NGC 1818 in the Large Magellanic Cloud

Abstract

We use high-resolution {\sl Hubble Space Telescope} imaging observations of the young ($\sim 15-25$ Myr-old) star cluster NGC 1818 in the Large Magellanic Cloud to derive an estimate for the binary fraction of F stars ($1.3<M_{\star }/M_{\odot }<1.6$). This study provides the strongest constraints yet on the binary fraction in a young star cluster in a low-metallicity environment ($[Fe/H]\sim -0.4$ dex). Employing artificial-star tests, we develop a simple method that can efficiently measure the probabilities of stellar blends and superpositions from the observed stellar catalog. We create synthetic color-magnitude diagrams matching the fundamental parameters of NGC 1818, with different binary fractions and mass-ratio distributions. We find that this method is sensitive to binaries with mass ratios, $q \ga 0.4$. For binaries with F-star primaries and mass ratios $q>0.4$, the binary fraction is $\sim 0.35$. This suggests a total binary fraction for F stars of 0.55 to unity, depending on assumptions about the form of the mass-ratio distribution at low $q$.

30 pages, 9 figures

References in corpus (10)

• The primordial binary population II: Recovering the binary population for intermediate mass stars in Sco OB2
• Visual Binaries in the Orion Nebula Cluster
• The massive star binary fraction in young open clusters I. NGC 6231 revisited
• The core binary fractions of star clusters from realistic simulations
• Do binaries in clusters form in the same way as in the field?
• The relationship between the prestellar core mass function and the stellar initial mass function
• Physical parameters of 15 intermediate-age LMC clusters from modelling of HST colour-magnitude diagrams
• The binary fraction in the globular cluster NGC 6397
• The initial mass function of the rich young cluster NGC 1818 in the Large Magellanic Cloud
• Beryllium abundance in turn-off stars of NGC 6752

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