Astronomical and Imaging Data

Useful Informations

NGC 4833 is a globular cluster located in the southern constellation of Musca, near the Coalsack Nebula. It’s partially obscured by the nebula’s dust, which makes it appear fainter and “reddened” to observers. Despite its lower visibility, it is a scientifically significant object for its extreme metal-poor composition and the presence of multiple stellar populations.

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Physical Characteristics

• Distance: Approximately 21,500 light-years from Earth.
• Apparent Magnitude: Its visual magnitude is about 6.91, but this is affected by the interstellar dust in the Coalsack Nebula.
• Mass and Age: NGC 4833 has an estimated mass of about 4.1×105 solar masses and is considered one of the oldest globular clusters, with an age of around 12.5 billion years.
• Metallicity: It is an extremely metal-poor cluster, with a metallicity of approximately -2.02 dex. This places it among the most metal-deficient globular clusters, similar to M92.

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Stellar Populations and Dynamics

• Multiple Stellar Populations: Like many other globular clusters, NGC 4833 is not home to a single stellar generation. Instead, it contains multiple stellar populations, evidenced by variations in the abundances of light elements like sodium and oxygen, which are linked to different generations of stars.
• Highly Eccentric Orbit: The cluster has a very eccentric orbit around the Milky Way. Its highly elongated path takes it close to the galactic bulge, where it experiences strong tidal forces. This interaction is believed to have caused the cluster to lose a significant fraction of its original mass.
• Oosterhoff Type II: Based on the properties of its RR Lyrae variable stars, NGC 4833 is classified as an Oosterhoff Type II cluster. These clusters are typically very metal-poor and have longer average pulsation periods for their RR Lyrae stars than Oosterhoff Type I clusters.

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