Now here’s something really scary for Halloween: Imagine two galaxies slamming into each other and creating a monstrous wraith with ghostly glowing eyes.
It’s not that far of a stretch. The Hubble Space Telescope captured just such an image, for a team of astronomers based at the University of Washington.
The visible-light picture, taken in June by Hubble’s Advanced Camera for Surveys, shows a galactic smash-up that took place about 700 million light-years away in the constellation Microscopium. The cosmic collision is known as Arp-Madore 2026-424 or AM 2026-424, because it’s noted that way in the Arp-Madore Catalogue of Southern Peculiar Galaxies and Associations.
AM 2026-424 is certainly peculiar: The head-on collision sparked the formation of a ring of hot blue stars around the edge of the merged galaxy’s “face.” Meanwhile, the smashed-up galaxies’ separate cores are still distinct, furnishing the face with those two glowing eyes.
In this week’s Halloween-themed image advisory, the Space Telescope Science Institute says only a few hundred such ring galaxies reside in our cosmic neighborhood. Astronomers say the outer ring structure should fade after about 100 million years. Within 1 billion to 2 billion years, the galaxies will become completely merged. All traces of the skull-like appearance will disappear, like a spook on the morning after Halloween.
This view of AM 2026-424 comes courtesy of a program that takes advantage of occasional gaps in Hubble’s observing schedule to squeeze in some opportunistic snapshots. A team led by UW astronomer Julianne Dalcanton took advantage of the opportunity to add to their survey of nearby interacting galaxies.
Such a survey could provide insights into how galaxies grow over time, through mergers like the one that created AM 2026-424. It could also point astronomers toward targets worth pursuing once NASA’s James Webb Space Telescope comes online in the early 2020s.
In their proposal to the Hubble observing program, Dalcanton and her colleagues — UW astronomers Benjamin Williams and Meredith Durbin — say that the interacting galaxies on their list are ideal targets for gap snapshots in part because “the public outreach value of any of the images is likely to be extremely high.” They got that right: Consider this tricked-out Skull Galaxy a visual treat for Halloween.