Glittering Lights

Globular Cluster 47 Tucanae

NGC 104, also known as 47 Tucanae, is a prominent globular cluster located in the constellation Tucana in the southern sky. It is one of the largest globular clusters and the second brightest in the Milky Way galaxy, making it easily visible to the naked eye from dark locations. First recorded in 1751 by Lacaille in his deep-sky catalogue, it was later identified as number "47" in Johann Elert Bode's catalogue who reorganized Lacaille's listed objects by constellation and Right Ascension, a number which is widely used still today. 47 Tucanae is distinguished by its compact and intensely bright core. With millions of stars concentrated in about 120 light-years of diameter, it is one of the most massive globular clusters in the galaxy. It is estimated to be about 11.5 billion years old, making it one of the oldest known globular clusters in the Milky Way. Despite its proximity to the Small Magellanic Cloud, which appears adjacent to it in the sky, 47 Tucanae is over fifteen times closer. Takahashi CCA250 (250/f5) - ZWO 6200MM - R (200m) G (240m) B (270m) - Osservatorio AMT (A.Lau/M.Lorenzi/T.Tse), Río Hurtado, Cile. Elaborazione immagini M.Lorenzi.

The Shell Game of NGC 3923

NGC 3923 is an elliptical galaxy found in Hydra, approximately 90 million light years away from Earth and spanning about 155,000 light years in diameter. It is an example of a shell galaxy, characterized by symmetrical shells of stars in its halo which are tens of thousands of light-years across. It is thought that the shells are formed when a big elliptical galaxy collides head-on with a smaller one, causing ripples of material to compress and spread outward, resulting in waves of star formation that produce the shells. Young stars are seen in the shells, making the theory consistent. However, there are also possibilities that off-center collisions can strip stars from a smaller galaxy, flinging them around a bigger galaxy, creating the shells, in a kind of galactic cannibalism. NGC 3923 has up to 42 symmetrical shells, the highest number of all known galaxies, but more subtle than those of other shell galaxies. NGC 3923 is accompanied by seven dwarf elliptical galaxies within a 25 arcminute radius, all of them part of the same galaxy group. At the bottom right of the image is visible NGC 3904, another elliptical Galaxy with a large halo. Notable among the other galaxies are the spiral galaxy PGC36882 in the top right of the image and the edge-on galaxy PGC37271 on the left, charaterized by a pronunced dust lane across its disk. Additionally, dozen other galaxies can be observed in the field of view, as well as several faint galactic cirri, which are filamentary dust clouds that belong to our own Galaxy. Takahashi CCA250 (250/f5) - ZWO 6200MM - L (1200m) R (90m) G (90m) B (90m) - AMT Observatory (A.Lau/M.Lorenzi/T.Tse), Río Hurtado, Chile. Image processing M.Lorenzi.

Galaxy Group Hickson 90 (HCG90)

The Galaxy Group Hickson 90 (HCG90), located just above the center of this image, is a small group of galaxies located in the constellation Piscis Austrinus, approximately 160 million light-years away from Earth. It is named after astronomer Paul Hickson, who compiled a catalog of compact groups of galaxies in the early '80s. HCG 90 consists of four major galaxies, NGC 7172, NGC 7173, NGC 7174, and NGC 7176, as well as a number of smaller galaxies and intergalactic gas. NGC 7173 and NGC 7176 appear to be smooth, normal elliptical galaxies without much gas and dust. In stark contrast, NGC 7174 is a mangled spiral galaxy, barely clinging to independent existence as it is ripped apart by its close neighbours. NGC7172 is an intriguing edge-on spiral galaxy showing a prominent lane of dust running across its length and is a so called Seyfert galaxy, a type of galaxy which intensely luminous nucleus is powered by matter accreting onto a supermassive black hole. Well documented in this long exposure are the group complex and interacting structures, including faint tidal tails, bridges, and shells, suggestion of the significant gravitational interactions and mergers the galaxies have undergone in the past. These strong tidal interaction surging through the galaxies has dragged a significant number of stars away from their home galaxies. These stars are now spread out, forming a tenuous luminous component in the galaxy group. The extension of these structures is visible in this image stretching well over half degree, the apparent size of the full Moon, which has seldom if ever been so clearly documented in a color image before. Studies of HCG 90 have yielded valuable insights into the dynamics of small galaxy groups and the effects of gravitational interactions on galaxy evolution. In particular, the group's complex morphology and relatively low velocity dispersion suggest that it is in the process of forming a compact group, which could eventually evolve into a single, massive galaxy. The "bright" blue star anchoring the center of this frame (HD209253) is in reality just beyond the visibility of unaided eyes. At the bottom of the image lays NGC 7187, a lenticular galaxy possessing a bright circular inner ring and a faint elongated outer ring and lacks prominent spiral arms. NGC 7187 is known to have a significant population of globular clusters, which are densely packed groups of stars that orbit the galaxy. Dozen of other galaxies of many different sizes, shapes and colors also populate this ramarkably rich cosmic canvas. Takahashi CCA250 (250/f5) - ZWO 6200MM - L (760m) R (90m) G (90m) B (110m) - AMT Observatory (A.Lau/M.Lorenzi/T.Tse), Río Hurtado, Chile. Image processing M.Lorenzi.