The Hubble Space Telescope (HST) has imaged four galaxies huddled close together in a stunning new photograph. The unusual families of stars in the photograph include NGC 839, NGC 838, NGC 835 and NGC 833.
The galaxies are part of a collection of bodies known as the Hickson Compact Group (HCG 16). The galaxy group also contains three other members not seen in the new images from the HST team.
"Compact groups represent some of the densest concentrations of galaxies known in the Universe, making them perfect laboratories for studying weird and wonderful phenomena. Hickson Compact Groups in particular, as classified by astronomer Paul Hickson in the 1980s, are surprisingly numerous, and are thought to contain an unusually high number of galaxies with strange properties and behaviors," Hubble Space Telescope mission managers reported.
Galaxies within the HCG 16 grouping are bursting with knots of star-forming regions. Cores of these galaxies are bright, bursting with activity. Three starburst galaxies, ripe with the formation of new stars, have been found within the group. Also included in HCG 16 are a pair of low-ionization nuclear emission-line region (Liner) galaxies, similar to the famous Sombrero Galaxy (M104). These contain a hot central core, emanating bursts of radiation. Another collection of stars in the group is a Seyfert 2 galaxy, featuring a powerful core, radiating vast amounts of energy in wavelengths of light that cannot be directly seen by human eyes.
One of the galaxies, NGC 839, is classified as a galactic cannibal, as astronomers believe it consumed another galaxy sometime in the past, growing in size. Long tails of gas can be seen coming off the left-most galaxy in the latest photograph of the group, apparently streaming from the galaxies on the opposite side of HCG 16.
Another member of the collection of stellar families, NGC 833, appears to have lost a portion of its mass through interactions with other galaxies. Astronomers now believe that most, if not all, galaxies are centered on supermassive black holes. The one observed in NGC 833, seen at the far right of the new image, shows evidence of its violent past.
The Wide Field Planetary Camera 2 onboard the Hubble Space Telescope was used to create the new photograph, when combined with data from the New Technology Telescope, a ground-based observatory in Chile.
Compact groups such as HCG 16 were first classified by astronomers in the 1980s. This is not the first time a compact group has been photographed by the HST team of astronomers.