Astronomical and Imaging Data

Useful Informations

NGC 6528 is a globular cluster located in the constellation Sagittarius. It is a scientifically important object because it is one of the very few metal-rich globular clusters residing in the crowded and dusty region of the Galactic bulge, a distinction that has made it a target for studying the properties of this specific stellar population.

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Physical Characteristics

• Distance: Located approximately 25,800 light-years from Earth.
• Apparent Magnitude: With an apparent magnitude of 9.60, it is a faint object that requires a medium-sized telescope for observation.
• Concentration: NGC 6528 is a Shapley-Sawyer Concentration Class III cluster, indicating a high central stellar concentration.
• Location in Baade’s Window: The cluster is located within Baade’s Window, a rare, relatively dust-free view of the Galactic bulge. This provides a clear line of sight to study the cluster’s properties and its relationship with other stars in the bulge.

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Stellar Populations and Metallicity

• High Metallicity: NGC 6528 is a metal-rich globular cluster, with a metallicity of approximately -0.11 dex. This makes it one of the most metal-rich globular clusters known, and its chemical composition is very similar to that of the stars in the Galactic bulge.
• Multiple Populations: Spectroscopic studies have shown that the cluster contains multiple stellar populations, with distinct groups of stars showing different abundances of light elements like nitrogen and oxygen.
• RR Lyrae Variable Stars: While metal-rich globular clusters typically have very few or no RR Lyrae variable stars, NGC 6528 has a small but present population of these stars. This makes it a valuable object for studying the properties of RR Lyrae stars in metal-rich environments.

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