Unlike spiral galaxies, with their flat shape and twisted arms, elliptical galaxies are featureless blobs without much structure. But then there’s NGC 3610—an elliptical galaxy with a bright and distinctly disc-like shape at its center. Astronomers say it’s a blast from this galaxy’s past, one that played an important role in its evolution.
Incredibly, virtually every object in this newly released Hubble image is a galaxy, save for a few foreground stars. At the center is elliptical galaxy NGC 3610 and its surprising disc. It’s unusual because discs are prominent features of spiral galaxies, like our Milky Way. But there’s a very good reason why it’s there.
When galaxies form, they typically take on the flat and spiral shape of our galaxy. Elliptical galaxies, which are quite disordered, form after the collision of two or more disc galaxies. When this happens, the internal structures of the original galaxies are destroyed. But the fact that NGC 3610 still retains its disc-like structure indicates that its collision happened only recently in cosmological terms.
Astronomers estimate its age at 4 billion years, and it’s proving to be an important object for studying the early stages of evolution in elliptical galaxies.
A similar thing is set to happen when our Milky Way collides with the Andromeda Galaxy (video above), which is projected to happen about 4 billion years from now.
Email the author at firstname.lastname@example.org and follow him at @dvorsky. Top image by ESA/Hubble & NASA, Acknowledgement: Judy Schmidt (Geckzilla)