Stunning New Image of the Sculptor Galaxy Captures the Cosmic Landscape in Thousands of Colors
The galaxy sits in a sweet spot that allows astronomers to study it in ways that can’t be applied to even our own Milky Way
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Some ten million light-years away from Earth sits a brilliant spiral galaxy officially called NGC 253 but known by many different names: Caldwell 65, Silver Dollar Galaxy, the Silver Coin. Most people, however, know this structure as the Sculptor galaxy, since it’s part of the Sculptor constellation in the southern sky. Outside of our local galactic neighborhood, it’s one of the closest galaxies to Earth.
An international team of researchers has recently published a spectacular new “thousand-color” image of the Sculptor galaxy, featuring unprecedented details of its components. They describe their work, conducted with the European Southern Observatory’s Very Large Telescope (VLT), in a forthcoming Astronomy & Astrophysics paper posted on the preprint server arXiv last week.
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“This mosaic constitutes one of the largest, highest physical resolution integral field spectroscopy surveys of any star-forming galaxy to date,” the researchers write in the study.
The image is, in fact, a veritable mosaic. The team used the VLT’s Multi Unit Spectroscopic Explorer (MUSE) instrument to observe the galaxy for over 50 hours, then stitched more than 100 exposures into the complete image we see today, which spans a 65,000-light-year-wide area of space.
Did you know? Discovery of the Sculptor galaxy
German-born British astronomer Caroline Herschel was the first to spot the Sculptor galaxy, which she found while searching for comets in 1783.A galaxy’s components, such as stars, gas and dust, emit or reflect many different wavelengths of light. Each wavelength corresponds to a color—and the new image sheds light on the Sculptor galaxy’s inner workings by capturing thousands of them. For comparison, traditional images only include a handful of colors, according to a statement from the European Southern Observatory.
“Since the light from stars is typically bluer if the stars are young or redder if the stars are old, having thousands of colors lets us learn a lot about what stars and populations of stars exist in the galaxy,” Kathryn Kreckel, a study co-author and an astronomer at Heidelberg University in Germany, tells Reuters’ Will Dunham. “Similarly for the gas, it glows in specific bright emission lines at very specific colors and tells us about the different elements that exist in the gas and what is causing it to glow.”
Initial observations of the detailed map have already revealed around 500 planetary nebulas—dust and gas from dying stars—that reside in the galaxy. Normally, astronomers can only identify about 100 planetary nebulas in galaxies that lie outside of Earth’s neighborhood. But finding these structures is important, because their properties help astronomers determine how far away their host galaxy is—a foundational measurement for other research on that galaxy.
And when it comes to distance, the Sculptor galaxy inhabits a cosmic sweet spot. This makes the galaxy favorably positioned for astronomers to observe and image it.
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“In the Milky Way, we can achieve extremely high resolution, but we lack a global view since we’re inside it. For more distant galaxies, we can get a global view, but not the fine detail. That’s why NGC 253 is such a perfect target,” Enrico Congiu, an astronomer at the European Southern Observatory in Chile and lead author of the study, tells Reuters. “It gives us a rare opportunity to connect the small-scale physics with the big-picture view.”
In other words, the image is so detailed that it allows scientists to study the galaxy as a whole, as well as zoom in almost to the level of individual stars, as Kreckel explains in the statement.
Moving forward, the map will help researchers investigate the properties of galactic gas and its role in star formation. “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,” Congiu adds in the statement. “Galaxies are incredibly complex systems that we are still struggling to understand.”
