Astronomical and Imaging Data

Useful Informations

The globular cluster Palomar 1 is a very faint and sparse stellar system located in the outer halo of the Milky Way galaxy, in the constellation Cepheus. It is one of the 15 faint globular clusters discovered on the photographic plates of the Palomar Observatory Sky Survey, which is how it got its name.

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Key Characteristics and Peculiarities

Palomar 1 is particularly notable for being an unusually young globular cluster. While the majority of the Milky Way’s globular clusters are ancient, having formed early in the galaxy’s history over 10 billion years ago, Palomar 1 is estimated to be only about 6.3 to 8 billion years old.

This relative youth, combined with its high location in the galactic halo (approximately 36.5 thousand light-years from the Sun), suggests an extraordinary origin. Astronomers theorize that Palomar 1 may have been accreted by the Milky Way, meaning it likely formed as part of a smaller dwarf galaxy that the Milky Way later gravitationally captured and subsequently began to consume. Its properties are similar to clusters associated with the Sagittarius Dwarf Spheroidal Galaxy stream (like Terzan 7 and Palomar 12).

The cluster is faint, with an apparent visual magnitude of around +13.18, and relatively metal-poor (its [Fe/H] value is approximately −0.60). It is also quite diffuse, classified as a loose concentration class (Class XII).

Unique Features

Faint and Sparse: It is one of the faintest and sparsest globular clusters known, with a relatively low luminosity and few member stars. This sparse nature makes it difficult to distinguish from foreground stars in some observations.

Tidal Tails: Extended tidal tails have been observed stretching about 1^∘ from the cluster center. This suggests it’s currently undergoing disruption due to the Milky Way’s gravitational tides, which is consistent with the cluster’s low density and mass.Unique Features

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