Scientists detect an enormous halo around the iconic Sombrero Galaxy — Space photo of the week

The central bulge and dark dust trail, which together resemble a traditional Mexican hat, give the Sombrero Galaxy (Messier 104, or M104) its nickname — but this new image of the galaxy from the powerful Dark Energy Camera reveals two never-before-seen features.

The defining hat-like shape of M104 is evident here with exceptional clarity. Its central bright nucleus, surrounded by a swarm of about 2,000 globular clusters (balls of ancient stars), glows intensely. The dust lane itself appears sharper and more continuous than in previous observations, cutting cleanly across the galaxy and reinforcing its distinctive "brimmed" silhouette. This dark band of cold dust and hydrogen gas is where stars are being born in the Sombrero Galaxy.

What sets this image apart are features that are usually too faint to detect. Surrounding the galaxy in this wide-angle image is an enormous, diffuse halo that extends far beyond the bright disk, stretching over three times the width of the sombrero itself and significantly increasing the galaxy's apparent size.

The image also captures a faint stellar stream stretching away from one side of the galaxy. This thin, curved feature is barely perceptible at first glance, but a closer inspection reveals it as a distinct arc of light beneath the galaxy as it's shown here. It breaks the galaxy's perfect symmetry and suggests past violent interactions with a smaller satellite galaxy.

The remarkable clarity of the image is due to the capabilities of the Dark Energy Camera, a 570-megapixel instrument mounted on the Víctor M. Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory in Chile. Operated by the National Science Foundation's NOIRLab, the system is designed to detect extremely faint light, allowing both the bright core and the dim outer structures of the galaxy to be captured in a single image.

The new image comes in the wake of the James Webb Space Telescope's first-ever mid-infrared observations of the Sombrero Galaxy in 2024, which it improved upon in June 2025.

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