About 4-6 million years ago, “something big” happened at the center of the Milky Way and NASA’s Stratospheric Observatory for Infrared Astronomy (Sofia) has brought back the latest pictures.

The “something big” was bursts of energy that created the Quintuplet Cluster (QC), Central Cluster and other massive star clusters at the center of the galaxy, says Matt Hankins of the University of Central Arkansas, lead author of a paper presented this week to the American Astronomical Society’s meeting in Long Beach, Calif., on an unprecedented view of that event.

Other galaxies have similar star bursts at their centers, whether associated with black holes or not, Hankins says. But the Milky Way’s is closer and easier to study.

Last year, Sofia, a highly modified Boeing 747SP mounted with a 100-in.-dia. infrared (IR) telescope, carried an IR camera called Forecast from Cornell University to study these bursts of energy. Forecast is designed to detect very faint objects by flying on Sofia at heights of as much as 45,000 ft. to escape atmospheric dust and water vapor that obscures IR images taken from ground observatories.

The instrument created a series of multiple exposures that revealed a ring of gas and dust — the galaxy’s circumnuclear ring (CNR) — and a neighboring Quintuplet Cluster, among other objects. CNR has a diameter of seven light years and rims a supermassive black hole at the center of the Milky Way.

Neither ground-based observatories nor the Hubble and Spitzer space telescopes have seen CNR or QC with such clarity. The black hole at the nucleus of the Milky Way has 4 million times the mass of the Sun.

“The focus of our study has been to determine the structure of the circumnuclear ring with the unprecedented precision possible with Sofia,” says Cornell’s Ryan Lau. “Using these data, we can learn about the processes that accelerate and heat the ring.”