The picture above may remind us of abstract expressionism or an action painting by Jackson Pollock, but it is really the latest observation of a group of galaxies called Stephan’s Quintet. While the group visually consists of five galaxies, just four are actually near each other, which makes it an incredible four-way merger. Astronomers have used the extremely rare group to understand the complex dynamic of galactic collisions.
The new picture was acquired by the Canada-France-Hawaii Telescope, located near the top of Mauna Kea, Hawaii. The global team employed the telescope’s capability of creating deep visible observations to look for structures having low surface brightness (LSB) that might have been missed by previous observations. And the search paid off.
The astronomers observed several LSB attributes stretching across the galaxies. Some arrangements were completely or partially visible in previous observations of the group. Some were entirely new. The latter category includes the discovery of a diffuse, reddish halo of stars around NGC 7317, an elliptical galaxy that is part of the Quintet.
The group has been utilized to comprehend star-formation episodes throughout mergers and the creation of tails of gas and stars, in addition to related phenomena such as gas ramming and also the creation of intergalactic systems. The reddish halo has consequences for every one of those. It suggests that the interaction has been going on for quite a while, therefore the stellar population in those tidal arrangements has aged and become redder. These findings are reported in the Monthly Notices of the Royal Astronomical Society.
The brightest member of the group is NGC 7320, the unconnected galaxy, which is actually located 39 million light-years away, closer than the 340 to 210 million light-years for the rest of the galaxies. This galaxy is currently going through an extreme star-formation stage.
The observations were done on a wide field of view and enabled for the evaluation of other objects unrelated to the Quintet. The telescope caught diffuse filaments surrounding NGC 7331, yet another foreground spiral galaxy visible in the complete image under. The researchers also noticed that the picture is contaminated by infrared emissions in the galactic cirrus, cloud-like structures that are located across the disc of the Milky Way
Stephan’s Quintet was the very first compact group ever discovered, celebrated for the first time in 1877 by French astronomer Édouard Stephan from whom it takes its name.