Palomar 5, a globular cluster discovered in 1950 by Walter Baade, is located approximately 76,000 light-years away in the constellation Serpens. This cluster is particularly notable for its extensive tidal streams—vast, elongated structures of stars that extend far beyond the cluster itself. These streams are remnants of Palomar 5’s ongoing interaction with the gravitational forces of the Milky Way.

Palomar 5 stands out among the Milky Way’s globular clusters due to the distinctive nature of its tidal streams. These streams stretch across tens of thousands of light-years and provide a striking visual testament to the dynamic processes shaping our galaxy. The formation of tidal streams occurs when the gravitational pull from the Milky Way distorts the cluster, stripping stars from its outer regions. Over time, these stripped stars form coherent structures that trace the cluster’s orbit around the galactic center.

The study of Palomar 5 and its tidal streams offers significant insights into both the cluster’s history and the broader dynamics of the Milky Way. By analyzing the distribution and motion of stars within these streams, astronomers can infer details about the galaxy’s gravitational potential, including the distribution of dark matter. Moreover, Palomar 5’s tidal streams serve as a natural laboratory for understanding the processes of tidal disruption and stellar dynamics in a galactic context.

Recent research such as the Gaia mission in combination with simulations have mapped these streams with unprecedented precision. These studies reveal that the streams contain not only stars originally from Palomar 5 but also interlopers—stars from other parts of the galaxy that have become gravitationally bound to the streams. This intricate interplay of stellar populations underscores the complexity of galactic evolution and the continual exchange of material within the Milky Way.

The long exposure time under pristine dark skies reveals many interesting background galaxies in the field of view. See the graphics below for some examples. Some of the brighter galaxies are not catalogized or identified as galaxies in catalogues such as the SDSS DR9 Survey. With 6h of Luminance it's possible to reach depths of SDSS r' and g' magnitudes of ~ 23 mag.



Photographed with the VdS Remote-Observatory in Hakos, Namibia under Bortle 1 conditions together with Yoshi Eschen.