The Sculptor galaxy is a stunning spiral galaxy, 11 million light-years away, and it is currently experiencing an intense period of star formation. It was discovered by Caroline Herschel in 1783, yet we can guarantee that a new view of the Sculptor Galaxy by the European Southern Observatory’s Very Large Telescope has never been seen before. This new map of the Sculptor contains thousands of colors.

Most astronomical images use wide-band filters that capture light across a large range of wavelengths. These can be, for example, red, blue, or green. But a lot of astronomical events emit at specific wavelengths, so using those allows you to distinguish specific emissions; or speaking in colors, your ruby from your rose or your cerulean from your lapis.

To make this thousand-color map, astronomers used over 50 hours with the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope. More than 100 exposures were stitched in this glorious new map of the Sculptor galaxy.

The pink light comes from ionized hydrogen in star-forming regions overlaid on a map of already formed stars (blue). Image credit: ESO/E. Congiu et al.

“Galaxies are incredibly complex systems that we are still struggling to understand. The Sculptor Galaxy is in a sweet spot,” lead author ESO researcher Enrico Congiu said in a statement. “It is close enough that we can resolve its internal structure and study its building blocks with incredible detail, but at the same time, big enough that we can still see it as a whole system.”

The observations cover an area of the galaxy 65,000 light-years across. Among the first studies of the map, the team looked for planetary nebulae, the regions of dust and gas that dying stars like the Sun create by shedding stellar material. The researchers confirmed around 500 in the Sculptor Galaxy, a record number that will have larger repercussions due to their milestone-like properties.

“Beyond our galactic neighbourhood, we usually deal with fewer than 100 detections per galaxy,” co-author Fabian Scheuermann, from Heidelberg University, puts the number into context.

“Finding the planetary nebulae allows us to verify the distance to the galaxy — a critical piece of information on which the rest of the studies of the galaxy depend,” added co-author Professor Adam Leroy, from Ohio State University.

This false-color composition shows wavelengths of light released by hydrogen (in an artistic pink rather than its actual blueish color), nitrogen (red), sulphur (yellow), and oxygen (green). The cone of white light is the outflow of gas from the galaxy’s central black hole. Image credit: ESO/E. Congiu et al.

It’s not just the end of stars but also the beginning, studying the details of star formation at a level that has not been possible before for galaxies beyond the local group.

“We can zoom in to study individual regions where stars form at nearly the scale of individual stars, but we can also zoom out to study the galaxy as a whole,” added Kathryn Kreckel from Heidelberg University.

This is just the beginning. The team plans to understand the gas flows, their evolution, and where and how this gas ends up forming stars. “How such small processes can have such a big impact on a galaxy whose entire size is thousands of times bigger is still a mystery,” added Congiu.

A paper describing the results is published in Astronomy & Astrophysics.