DDO 210, Aquarius Dwarf – a dwarf galaxy in the constellation Aquarius
On the western edge of the constellation Aquarius lies one of the most inconspicuous galaxies in our cosmic neighborhood. DDO 210, also known as the Aquarius Dwarf Galaxy, was not discovered until 1959 by Sidney van den Bergh on photographic plates from the Palomar Sky Survey. Its low surface brightness long cast doubt on its membership in the Local Group. It was finally confirmed by precise distance measurements of its brightest giant stars.
Astronomers classify DDO 210 as a transitional type between irregular and spheroidal dwarf galaxies. There are almost no signs of past interactions. The galaxy moves through space in isolation. Only two other members of the Local Group, SagDIG and NGC 6822, are found in its wider vicinity. However, both of these neighbors are more than a million light-years away. Its isolation is considered a possible reason for the delayed star formation. Among the dwarf galaxies of the Local Group, such behavior is found in only a few other systems, such as Leo A.
In the image, DDO 210 appears as an elongated, mottled bluish nebula. The brightest stars in the galaxy, with visual magnitudes between 21 and 22 mag, can already be resolved. However, most of the stars are significantly fainter than 23 mag and blend into the galaxy’s background glow.
| Date: | 10.09.-17.09.2025 |
| Optics: | Planewave CDK 14 with Televue 0.8x reducer |
| Aperture: | 350 mm |
| Focal Length: | 2050 mm |
| Camera: | QHY268M |
| Exposure: | L:R:G:B 60:33:30:30 x 600 s |
| Location: | Gemsbock Observatory, Rooisand Desert Ranch, Namibia |
| Processing: | PixInsight, Photoshop |
| Diameter: | 3,250 light years |
| Distance: | 3,2 million light years |
