Free Astronomy Magazine March-April 2024

34 MARCH-APRIL 2024 ASTRO PUBLISHING erated by NSF’s NOIRLab, the galaxy’s intricate dust lanes are a sight to behold. NGC 4753 is located about 60 million light-years away in the constellation Virgo. It is a mem- ber of the NGC 4753 Group of gal- axies within the Virgo II Cloud — a series of at least 100 galaxy clusters and individual galaxies stretching off the southern edge of the Virgo Supercluster. NGC 4753’s distinct dust lanes, ap- pearing to twist and turn around the galaxy’s nucleus, have long in- trigued astronomers, and are the ir- regular features that give it its ‘peculiar’ classification. Seen nearly edge-on from Earth, this galaxy can appear rather mystifying. But in 1992 a team of astronomers led by Tom Steiman-Cameron, now a sen- ior research scientist at Indiana Uni- versity, published a detailed study of NGC 4753 in which they found that its complicated shape is likely the re- sult of a merger with a small com- panion galaxy. “ Galaxies that gobble up another galaxy often look like train wrecks, − said Steiman-Cameron − and this is a train-wreck galaxy.” Galaxy mergers occur when two (or more) galaxies collide, causing their material to mix and significantly al- tering the shape and behavior of each galaxy involved. In the case of NGC 4753, it is thought that the once standard lenticular galaxy merged with a nearby gas-rich dwarf galaxy about 1.3 billion years ago. The gas of the dwarf galaxy, coupled with bursts of star forma- tion triggered by this galactic colli- sion, injected the system with vast amounts of dust. The galaxy’s in- ward spiral due to gravity then caused the accumulated dust to by NOIRLab − Josie Fenske Gemini South captures the aftermath of past merger A n astounding number of galaxies populate the ob- servable Universe, with re- cent estimates placing that number anywhere from 100 billion to 2 tril- lion. And, akin to snowflakes, no two are exactly alike. But depending on their visual appearance and phys- ical features they can be divided into four broad classes: elliptical, lenticu- lar, irregular and spiral, with many subclasses in between. However, galaxies are dynamic objects that evolve over time as they interact with their surrounding environ- ment, meaning that an individual galaxy may fall under multiple clas- sifications throughout its lifetime. Such is thought to be the case with NGC 4753, which astronomers hy- pothesize began as a normal lentic- ular galaxy but morphed into the more specific peculiar class after a merger with a nearby dwarf galaxy over a billion years ago. Discovered by astronomer William Herschel in 1784, NGC 4753 displays some truly fascinating features. In this image captured by the Gemini South telescope, one half of the In- ternational Gemini Observatory op-