This Hubble Space Telescope image features IC 776, a dwarf galaxy in the Virgo cluster, showcasing its complex morphology including a disturbed disk and star-forming regions. This image is part of a study focusing on the sources of X-rays in dwarf galaxies, which are crucial for understanding galaxy evolution and cosmology.Credit: ESA/Hubble & NASA, M. Sun
IC 776, a dwarf galaxy located in the Virgo galaxy cluster, is the subject of intensive study due to its emission of X-rays, offering insights into the processes influencing galaxy evolution and cosmology.
Featured in this Hubble Picture of the Week this week is the dwarf galaxy IC 776. This swirling collection of stars new and old is located in the constellation Virgo — in fact, in the Virgo galaxy cluster — 100 million light-years from Earth. While a dwarf galaxy, it’s also been classified as an SAB-type or ‘weakly barred’ spiral, one study naming it a “complex case” in morphology. This highly detailed view from Hubble demonstrates that complexity well. IC 776 has a ragged, disturbed disc that nevertheless looks to spiral around the core, and arcs of star-forming regions.
This image is from an observation program dedicated to the study of dwarf galaxies in the Virgo cluster, searching for sources of X-rays in such galaxies. X-rays are often emitted by accretion discs, where material that is drawn into a compact object by gravity crashes together and forms a hot, glowing disc. The compact object can be a white dwarf or neutron star in a binary pair, stealing material from its companion star, or it can be the supermassive black hole at the heart of a galaxy, devouring all around it.
Dwarf galaxies like IC 776, traveling through the Virgo cluster, experience a pressure from the intergalactic gas which can both stimulate star formation and feed the central black hole in a galaxy. That can create energetic accretion discs, hot enough to emit X-rays.
While Hubble is not able to see X-rays, it can coordinate with X-ray telescopes such as NASA’s Chandra, revealing the sources of this radiation in high resolution using visible light. Dwarf galaxies are thought to be very important for our understanding of cosmology and the evolution of galaxies. As with many areas of astronomy, the ability to examine these galaxies across the electromagnetic spectrum is critical to their study.
