Astronomical and Imaging Data

Useful Informations

NGC 6273, also known as Messier 19 (M19), is a globular cluster located in the constellation Ophiuchus. This ancient stellar system is notable for its highly concentrated core and its proximity to the Milky Way’s galactic center.

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Key Physical Properties

M19 is situated approximately 28,700 light-years from Earth. Its location near the galactic center (only about 5,200 light-years away from the core) means it is subject to the intense gravitational forces of the Milky Way’s massive bulge.

• Structure: The cluster is highly concentrated and has a very dense core, classified as a Shapley-Sawyer Concentration Class II. This indicates that the stars are extremely tightly packed toward the center, making it difficult to resolve individual stars in this region. This high concentration is a result of both its initial formation and its long-term dynamical evolution.
  M19 is one of the most oblate of the known globular clusters. This flattening may not accurately reflect the physical shape of the cluster because the emitted light is being strongly absorbed along the eastern edge. When viewed in the infrared, the cluster shows almost no flattening
• Tidal Forces: Due to its close orbit around the galactic center, M19 is heavily influenced by tidal forces. This is thought to have stripped away some of its outer stars and may contribute to its compact, centrally concentrated structure.

Scientific Significance

M19’s unique location and properties make it a valuable target for research.

• Galactic Potential: Its orbit around the galactic center provides a crucial test case for models of the Milky Way’s gravitational potential, particularly in the inner halo and bulge.
• Variable Stars: The stellar population includes four Cepheids and RV Tauri variables, plus at least one RR Lyrae variable for which a period is known

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