Astronomical and Imaging Data

Useful Informations

NGC 6934 is a globular cluster located in the northern constellation of Delphinus (the Dolphin). It’s a relatively distant and faint cluster, residing in the outer halo of the Milky Way, which makes it an excellent object for studying the properties of our galaxy’s outskirts.

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Key Scientific Properties

• Age and Metallicity: NGC 6934 is an ancient cluster, with an estimated age of about 11.6 billion years. Its stars are metal-poor, with a metallicity ([Fe/H]) of approximately -1.47, meaning their abundance of elements heavier than hydrogen and helium is significantly lower than the Sun’s. This low metallicity is a key characteristic of old stellar populations that formed in the early universe before it was enriched with heavier elements from supernovae.
• Distance and Location: The cluster is located approximately 52,000 light-years from Earth. Its position in the galactic halo is notable, as it is well outside the main disc of the Milky Way. NGC 6934 follows a highly eccentric orbit through the galaxy, with an eccentricity of 0.81. This highly elongated path suggests it may be a “tidal tail” remnant or share a common dynamic origin with other clusters.
• Variable Stars: NGC 6934 is particularly rich in variable stars, which are stars that change in brightness over time. It has been classified as an Oosterhoff type I cluster, a classification based on the period-luminosity relation of its RR Lyrae variable stars. At least 79 RR Lyrae stars have been identified in the cluster, along with a few other types of variables like SX Phoenicis stars. Studying these variables is crucial for determining the cluster’s distance and age.
• Structure: NGC 6934 has a Shapley-Sawyer concentration class of VIII, indicating a low to moderate concentration of stars. Its core is not as densely packed as some other, more prominent globular clusters, which makes it a good target for resolving individual stars in its central region with high-resolution telescopes.

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