An international team of astronomers using the Dark Energy Survey (DES) has discovered a new ultra-diffuse dwarf galaxy. The new galaxy is named NGC 55-dw1, a satellite of galaxy NGC 55. Ultra-diffuse galaxies (UDGs) are galaxies with extremely low density and few stars relative to their size. Scientists are still trying to understand why these large but faint galaxies aren’t torn apart by the gravity of their host galaxy clusters. NGC 55-dw1 was discovered based on six years of large-scale observations by DES. The galaxy is located about 6.5 million light-years from Earth in the constellation Sculptor and only 98,000 light-years from its host galaxy NGC 55. NGC 55-dw1 has an absolute magnitude of -8.0 mag, a half-light radius of about 7,200 light-years, and a total stellar mass of about 142,000 solar masses. The most attractive aspect of NGC 55-dw1 is its large spatial extent relative to its brightness. It has a low surface brightness and is the largest and most diffuse galaxy known at its luminosity. The galaxy’s high ellipticity and close distance from its host galaxy suggest tidal interaction, but further studies are needed to confirm this.

The discovery of NGC 55-dw1 adds to our understanding of the number of dwarf galaxies in the local volume. However, due to the limitations of ground-based imaging, further studies will be needed to confirm tidal interactions and understand the origin and properties of this faint ultra-diffuse dwarf galaxy.

Source: DOI : 10.48550/arxiv.2309.04467 – Revue : arXiv