A galaxy that reflects a very early version of our galaxy, the Milky Way, has been discovered. Dubbed the Bengal Fire, the galaxy is embedded in a system of globular clusters and satellite galaxies and seems to engulf them as it grows. Study published Monthly Notices of the Royal Astronomical Society.

Sparkler’s discovery was made based on initial data from the James Webb Space Telescope. Named after the two dozen orbiting globular clusters, Sparkler offers a unique insight into the formation history of the Milky Way at its inception. Globular clusters are dense clusters of about one million stars. Currently, the Milky Way contains about 200 globular clusters.

Bengal fire can be found in the southern sky in the constellation Volana. The galaxy and globular cluster system were discovered with a redshift of 1.38, which means we see the galaxy about 9 billion years ago, about 4 billion years after the Big Bang. The observations were made possible by the illuminating effect of the new JWST and the gravitational lens placed in front of the galaxy.

The research was led by Professor Duncan Forbes of Swinburne University in Australia and Professor Aaron Romanowski of San Jose State University in the USA. They now studied the ages and metallicity distributions of a dozen compact star clusters surrounding Sparkler to determine if they resemble younger versions of clusters around the Milky Way. A few are ancient and metal-rich, similar to those seen in the bulge of the Milky Way, and are therefore likely globular clusters.

A few star clusters were middle-aged and metal-poor; these clusters are associated with a companion galaxy joining the Sparkler galaxy; it appears to be engulfing the companion galaxy and globular cluster system, just as the Milky Way did in the past.

Although the sparkler is currently only 3% of the mass of the Milky Way, it is expected to grow over cosmic time to equal the mass of the Milky Way in the modern Universe. The team will need deeper images to explore more clusters and moons around Sparkler.

“We are witnessing it firsthand as this galaxy forms its mass in the form of a dwarf galaxy and several globular clusters,” says Professor Forbes. “We are excited about this unique opportunity to study both the formation of globular clusters and the formation of the Milky Way at a time when the universe is only 1/3 the age of now,” he adds.

Co-author Professor Aaron Romanowski comments: “The origin of spherical clusters is a long-standing mystery, and we are delighted that JWST can go back in time and see them in their youth.”