| Abstract : | A low-surface-brightness galaxy, or LSB galaxy, is a diffuse galaxy with a surface brightness that is at least one magnitude fainter than the ambient night sky. The LSB galaxies may account for up to 15 % of the mass of the universe. However, they are difficult to study due to the observational challenges in detecting them because of their inherent faintness. In this study, we present serendipitous discovery of a nearby diffuse galaxy that shows intense star formation in its inner disk using Ultraviolet Imaging Telescope (UVIT) and Multi-Unit Spectroscopic Explorer (MUSE) data. The galaxy was not detected earlier due to its superposition with the background galaxy NGC 6902A. They were together mistakenly classified as an interacting system. While studying a known interacting galaxy NGC6902A we noticed that south-west outer region of galaxy NGC 6902A shows diffuse blue emission. This south-western region shows prominent star forming regions in the FUV image. Further investigations revealed that these star forming regions are at a distance of around 136 million light-years, whereas the distance of NGC 6902A is around 825 million light-years. This means that the diffuse blue emission was from a foreground galaxy, which we discovered using FUV and MUSE data. We named it UVIT J202258.73-441623.8 based on the UVIT telescope that helped us to discover the galaxy. Our study suggests that powerful instruments such as UVIT and MUSE thus opens a gateway to searching for similar cases, where blue diffuse tidal features in interacting galaxies may not be the remnant of a merger but instead a separate foreground and/or background galaxy. |
