In search of dark energy, a telescope stopped to observe the Lobster Nebula

If you thought dark matter was hard to study, studying dark energy is even harder. Dark energy is perhaps the most subtle phenomenon in the universe. It is the driving force behind the evolution of the cosmos, but its effects are only visible on an intergalactic scale. So, to study dark energy in detail, you need a large number of observations of large areas of the sky.

That’s why, ten years ago, the Department of Energy worked with astronomers to build the Dark Energy Camera (DECam). It is the highest resolution astronomical camera ever built, with over 60 imaging CCDs, and captures images at 570 megapixels. It was installed at the 4-meter Víctor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile, where it has a field of view more than 2 degrees wide, four times the apparent width of the Moon.

Between 2013 and 2019, DECam captured an average of 400 to 500 images per night, looking at distant supernovae, measuring the scale at which galaxies cluster together, and studying the weak gravitational lensing of intergalactic dark matter. This data has given us a better understanding of dark energy and has helped astronomers limit observations to better fit theoretical models to observation.

But as DECam reached its first decade of operation, the team decided to do something a little different. A high-resolution wide-field camera is great for capturing data, but it’s also great for capturing amazing images. So the team pointed it at the NGC 6357 nebula, also known as the Lobster Nebula. It’s about 8,000 light-years from Earth in the constellation Scorpius and is an intense region of star formation. You can see the results in the image below, which is quite stunning.

The image spans about 400 light-years and shows bright young stars among dense regions of gas. To capture the detail in this image, the DECam team used narrow band filters to take images of specific colors within the nebula. Then combine and color these images to create the final image. It’s an amazing demonstration of what the DECam can do.

Of course, with a decade of work under its belt, the DECam has no plans of stopping anytime soon. It recently captured its millionth image, and over time it could capture a million more.

You can see the very high resolution images at NOIRLab Photo Release.