Free Astronomy Magazine March-April 2025

12 MARCH-APRIL 2025 ASTRO PUBLISHING T his excerpt shows some of the interesting features in the image of the Southern Pinwheel Galaxy taken with the Dark Energy Camera. [CTIO/NOIRLab/DOE/NSF/AURA − Image processing: T.A. Rector (Uni- versity of Alaska Anchorage/NSF NOIRLab), D. de Martin (NSF NOIR- Lab) & M. Zamani (NSF NOIRLab)] well-defined spiral arms, filled with pink clouds of hydrogen gas where new stars are forming. Interspersed amongst these pink regions are bright blue clusters of hot, young stars whose ultraviolet radiation has blown away the surrounding gas. At the galaxy’s core, a yellow central bulge is composed of older stars, and a weak bar connects the spiral arms through the center, funneling gas from the outer regions toward the core. DECam’s high sensitivity captures Messier 83’s extended halo, and myriad more distant galaxies in the background. Just as Messier 83 is filled with countless newly formed stars, the galaxy is also host to many dying stars. In the past century, as- tronomers have witnessed a total of six stellar explosions, called super- novae, in Messier 83 — a number matched by only two other galaxies. And while we have only detected these six stellar deaths, the galaxy is estimated to be filled with hun- dreds of thousands of ‘ghosts’ of dead stars called supernova rem- nants. In 2006 a mysterious feature of Messier 83 was discovered by NSF NOIRLab astronomer Ruben Diaz and an international team of as- tronomers using the Gemini South telescope, one half of the Interna- tional Gemini Observatory, funded in part by the NSF and operated by NSF NOIRLab. At the heart of this galaxy, they discovered a previously unseen concentration of mass resembling a second nucleus, likely the remnant of another galaxy that is being consumed by Messier 83 in an ongoing collision — possibly the same collision responsible for the starburst activity. The two nuclei, which likely contain black holes, are ex- pected to merge to form a single nucleus in another 60 million years. ! T his video tells us about the lat- est observation of the South- ern Pinwheel Galaxy by the Dark Energy Camera. [Images, Videos, and Animation: CTIO/NOIRLab/DOE/ NSF/AURA/M. Garrison − Image Processing: T.A. Rector (University of Alaska Anchorage/NSF NOIR- Lab), D. de Martin (NSF NOIRLab) & M. Zamani (NSFNOIRLab) − Music: Stellardrone - Twilight]