A Giant Fuzzball

NASA, ESA and Michael West (ESO)

Occa­sion­ally, I find huge fur­balls tucked away in the far cor­ners of my house. They sit all by them­selves, alone, after rolling around gath­er­ing up other fur­balls and assorted smaller pieces of fuzz. Like my huge fuzzballs, ESO 306–17 dom­i­nates its area of the uni­verse. Explore the image from NASA’s Hub­ble Space Tele­scope and you’ll see plenty of other galax­ies. Count up all those spi­ral galax­ies. Those galax­ies, how­ever, are either far­ther away or, like the two bright galax­ies at the bot­tom of the image, much closer than the giant ellip­ti­cal galaxy.

Astronomers refer to galax­ies like ESO 306–17 as part of a fos­sil group because they are lon­ers; iso­lated galax­ies through­out the uni­verse. The galaxy may be all that remains of a once large clus­ter of galax­ies. Grav­ity brings galax­ies together. Galax­ies merge and larger galax­ies snack on smaller galax­ies. Even our own Milky Way appears to have swal­lowed up a few smaller galax­ies that strayed too close. ESO 306–17 may have eaten all of the galax­ies in its group and now shines alone sur­rounded by dark mat­ter and hot gas. ESO 306–17 may be a colos­sal cos­mic cannibal.

Zoom in super close and you can see faint glob­u­lar clus­ters shin­ing in the galaxy’s halo. These tightly bound groups of stars fended off the merger and are the only wit­nesses to the galac­tic feasts. Astronomers also hope that by search­ing through­out the glow of ESO 306–17, they might find dwarf galax­ies; the cores of the smaller galax­ies stripped and devoured by their larger counterpart.

ESO 306–17 lies about a half-billion light-years from Earth toward the south­ern con­stel­la­tion Columba, the Dove.