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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 $q$.
The binary fraction of unevolved massive stars is thought to be 70-100% but there are few observational constraints on the binary fraction of the evolved version of a subset of these stars, the red supergiants (RSGs). Here we identify a complete samp
Hubble Space Telescope V,I photometry of stars in the Large Magellanic Cloud Cluster NGC 1866 shows a well defined cluster main sequence down to V=25 mag, with little contamination from field or foreground stars. We use the main sequence fitting proc
We present Hubble Space Telescope ACS deep photometry of the intermediate-age globular cluster NGC 1783 in the Large Magellanic Cloud. By using this photometric dataset, we have determined the degree of ellipticity of the cluster ($epsilon$=0.14$pm$0
We present {it Hubble Space Telescope} {it V,I} photometry of the central region of the LMC cluster NGC 1866, reaching magnitudes as faint as V=27 mag. We find evidence that the cluster luminosity function shows a strong dependence on the distance fr
Despite their close proximity, the complex interplay between the two Magellanic Clouds, the Milky Way, and the resulting tidal features, is still poorly understood. Recent studies have shown that the Large Magellanic Cloud (LMC) has a very extended d