NGC 4567/4568 - Butterfly-Galaxies

This deep-sky image captures a fascinating and immensely dynamic region in the heart of the Virgo Galaxy Cluster within the constellation Virgo. The center of the image is dominated by the famous interacting galaxy pair NGC 4567 and NGC 4568, which is primarily listed in professional catalogs as Arp 318, but also as VV 219 or KPG 347. Due to their characteristic shape, these two spiral galaxies are often called the Butterfly Galaxies or, traditionally, the Siamese Twins. The pair is located roughly 60 million light-years away from Earth. In this photograph, the cosmic spectacle unfolds in real time: the two systems are in the early stages of a titanic collision. The two galaxies lie practically parallel next to each other, with NGC 4567 located on the eastern (left) side, spanning a diameter of about 65,000 light-years, while its larger partner NGC 4568 lies to the west (right), stretching across around 91,000 light-years. Although their galactic disks are already interpenetrating, the bright galactic cores of the two systems are currently still about 20,000 light-years apart. However, the immense gravitational force is already visibly distorting their outer dust and stellar lanes. In an estimated 500 million years, their cores will merge completely to form a single, giant elliptical galaxy.

The image captures the objects in a nearly horizontal alignment, which provides a clear orientation: in this composition, North is exactly up and East is on the left side. The galaxies form a striking chain from left to right. On the far left of the frame, level with the main pair, this row begins with the elliptical galaxy NGC 4564. To the right of the Butterfly Galaxies, the line continues: here, the faint dwarf galaxy PGC 42075 glows softly first, followed further to the right by the spiral galaxy IC 3570. All of these surrounding companions – including the dwarf galaxy PGC 169592 in the upper section of the image and the scattered systems PGC 169627 and PGC 165260 further below – lie at a distance of 55 to 60 million light-years and are true physical neighbors in the Virgo Cluster.

The most breathtaking contrast, however, is revealed by looking into the vertical depth of space above the Butterfly pair. Above the central galaxies, the background galaxy PGC 169598 is visible. Looking even further up and to the left, past two prominent, vertically aligned stars, you come across a sensational detail: an extremely distant galaxy duo consisting of PGC 1391211 and its companion PGC 3550884, which is offset by about 45 degrees. These tiny, slightly fuzzy points of light are not members of our local supercluster. Their light traveled an unimaginable journey of over one billion light-years before hitting the camera sensor. The fact that these two distant galaxies appear so clearly resolved as distinct, diffuse structures next to each other turns this image into a true time machine, impressively demonstrating just how infinitely deep the cosmos extends behind the prominent foreground galaxies.