Nasa is celebrating Hubble’s 32nd birthday with the stunning look of five galaxies anointed “The Hickson Compact Group 40” in a gravitational dance.
“This menagerie includes three spiral-shaped galaxies, an elliptical galaxy, and a lenticular (lens-like) galaxy. Somehow, these different galaxies crossed paths in their evolution to create an exceptionally crowded and eclectic galaxy sampler.”
One possible explanation is that there’s a lot of dark matter (an unknown and invisible form of matter) associated with these galaxies. If they come close together, then the dark matter can form a big cloud within which the galaxies are orbiting. As the galaxies plow through the dark matter they feel a resistive force due to its gravitational effects. This slows their motion and makes the galaxies lose energy, so they fall together.- NASA
“Though over 100 such compact galaxy groups have been catalogued in sky surveys going back several decades, Hickson Compact Group 40 is one of the most densely packed. Observations suggest that such tight groups may have been more abundant in the early universe and provided fuel for powering black holes, known as quasars, whose light from superheated infalling material blazed across space. Studying the details of galaxies in nearby groups like this helps astronomers sort out when and where galaxies assembled themselves, and what they are assembled from”.- NASA informed.