The Milky Way's Hidden Features Will Amaze You In This Stunning 1 Million Hour Color Image
Astronomers from the International Centre of Radio Astronomy Research (ICRAR), primarily based at Curtin University in Australia, have released the most detailed low-frequency radio image of the Milky Way's galactic plane ever assembled. Rather than the starry, luminous band we're more familiar with, the latest images show a vibrant tapestry woven from the invisible colors of radio light. Specifically, the mosaic captures the Southern Hemisphere's view of the Milky Way, charting a section of the sky that had previously remained largely obscured at these long wavelengths, a region that spans 95% of the galactic plane visible from the south.
This image was constructed from data gathered by the Murchison Widefield Array (MWA), a unique radio telescope comprised of 4,096 spider-like antennas dotting the quiet Western Australian outback. The MWA's wide-field capabilities were leveraged across two extensive surveys—the OG GaLactic and Extragalactic All-sky MWA (GLEAM) survey and the subsequent, upgraded GLEAM-eXtended (GLEAM-X) survey.
The effort to process and compile this enormous dataset was enormous, requiring 18 months of PhD student Silvia Mantovanini's time plus over a million hours of processing time on the Pawsey Supercomputing Research Center's supercomputers. The final product boasts twice the resolution, ten times the sensitivity, and double the sky coverage compared to the most recent 2019 compilation.
What makes this radio image special is its use of radio color to disentangle complex astrophysical phenomena. Using a span of low radio frequencies (from 72MHz to 231MHz), astronomers were able to distinguish between different types of galactic structures based on their emission properties. Specifically, the emission coming from the final, explosive moments of dead stars (i.e. supernova remnants) appears prominently in large red or orange circular shapes, which correspond to lower-frequency emission. Conversely, HII ionized gas clouds where new stars are actively forming, shine brightly in blue, indicating emission at higher radio frequencies. This color coding is critical because in traditional images, these distinct features often look similar.
The ICRAR team catalogued nearly 98,000 radio sources across the southern Galactic Plane, encompassing a diverse mix of objects, including pulsars, planetary nebulae, and even distant background galaxies. Ms. Mantovanini's work, which focuses on supernova remnants, is expected to help locate the thousands of star-explosion remnants that astronomers believe are still lurking undiscovered in the galaxy's dense, obscuring planes. Furthermore, by measuring the brightness of pulsars at different GLEAM-X frequencies, the team hopes to gain a deeper understanding of how these enigmatic objects emit radio waves and precisely where they are located.
