A spectacular new view of two dwarf galaxies caught in the middle of a cosmic collision reveals a glowing gas bridge, streams of newborn stars and the ongoing gravitational tug-of-war reshaping both galaxies.
Taken by the James Webb Space Telescope (JWST), the new image captures the dwarf galaxies NGC 4490 and NGC 4485 stretching, tugging and warping one another in a dramatic gravitational dance unfolding 24 million light-years away. Because dwarf galaxies closely resemble the low-mass, gas-rich, metal-poor systems that populated the early universe, their collisions and gas exchanges provide a valuable window into how the first galaxies formed and evolved, according to a statement from the European Space Agency.
“Aside from the Milky Way’s own dwarf companions — the Large and Small Magellanic Clouds — this is the closest known interacting dwarf-dwarf system where astronomers have directly observed both a gas bridge and resolved stellar populations,” ESA officials said in the statement.
While the galactic pair, collectively called Arp 269, has been previously studied using observations from the Hubble Space Telescope, Webb’s infrared vision has revealed the system in unprecedented detail. Using Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), scientists now have an up-close view of individual stars and the fine structure of the gas flowing between the galaxies.
“By dissecting these galaxies star by star, researchers were able to map out where young, middle-aged, and old stars reside, and trace the timeline of the galaxies’ interaction,” ESA officials said.
Their analysis suggests the dwarf galaxies swept past each other about 200 million years ago. During that encounter, NGC 4490 siphoned gas from its smaller partner, creating the visible bridge of exchanged material we see today and fueling waves of star formation — some of which kicked off as recently as 30 million years ago.
“By capturing the history of the galactic dancers NGC 4490 and NGC 4485, Webb has revealed new details in how dwarf galaxies interact, giving us a glimpse of how small galaxies near and far grow and evolve,” ESA officials said in the statement.
