Astronomical and Imaging Data

Useful Informations

Terzan 3 is a globular cluster located in the constellation Sagittarius. It is one of a handful of globular clusters discovered by Armenian astronomer Agop Terzan and is classified as a “bulge cluster” due to its location within the heavily obscured central region of the Milky Way. Its study is challenging but provides valuable insight into the formation and evolution of the galactic bulge.

Key Scientific Properties

• Distance and Extinction: Terzan 3 is located approximately 15,000 light-years from Earth. Its position deep within the Milky Way’s disk means its light is significantly affected by interstellar dust and gas. This causes a phenomenon called reddening, where shorter wavelengths of light (like blue) are scattered and absorbed, making the cluster appear redder than it actually is. Astronomers must account for this effect, known as extinction, to accurately determine its properties.
• Metallicity: Unlike many other halo globular clusters which are extremely metal-poor, Terzan 3 is considered metal-rich for a globular cluster, with a metallicity ([Fe/H]) of approximately -0.74. This higher metallicity is a characteristic shared by other clusters located in the galactic bulge, suggesting they formed from gas that had already been enriched by previous generations of stars.
• Stellar Populations: Although a detailed analysis is challenging due to the interstellar reddening, observations suggest that Terzan 3, like many other globular clusters, hosts multiple stellar populations. This is a common feature in globular clusters where stars do not all form at the same time but in distinct generations with slightly different chemical compositions.
• Structure: Terzan 3 is a relatively low-concentration cluster, meaning its stars are less tightly packed than in many other globular clusters. This is in contrast to the dense cores of some well-known clusters and contributes to its appearance in telescopic images.

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