My neighbor stopped by the other night with the Christmas wreath we’d ordered. First, I stuck my nose in it to breathe in the citrusy tang of balsam fir needles. Delicious! The next day I hung it outside the door and admired the green whirls and big red ribbon. A cheerful sight on grayovercastday #14 here in my hometown.
Later that day, a press release arrived with a photograph of the galaxy NGC 4696 bearing an uncanny resemblance to my wreath but instead of balsam, its whorls were fashioned of glowing gas and dust. The elliptical galaxy lies in the constellation Centaurus the Centaur about 150 million light years from Earth or 60 times farther than the Andromeda Galaxy. Most elliptical galaxies have an elliptical or oval shape and look like featureless glows through the telescope, but this cosmic oddity’s bright core is wrapped in system of dark, swirling tendrils.
NGC 4696 is a member of the Centaurus Galaxy Cluster, a swarm of hundreds of galaxies all sitting together, bound together by gravity, about 150 million light-years from Earth. It stands out not only as the brightest member but as one of the biggest and brightest galaxies in the known universe. You can even see it in a telescope as small as 6-inches. Being brilliant is one thing, but it’s the galaxy’s unique wreathy structure that piqued astronomers’ interest to study it in more detail.
An international team of scientists, led by astronomers from the University of Cambridge, UK, the Hubble Space Telescope to explore the curious pink tendrils. Each has a width of about 200 light years but despite their static appearance in the photo, they’re anything but. Instead, they’re knit together and spiral inwards towards the center of NGC 4696, where lurks a lively supermassive black hole. Matter streaming down the hole is heated to extreme temperatures, flooding the galaxy’s inner regions with energy, heating the gas there and sending streams of heated material outwards. I think of how heat from a flaming bonfire sends cascades of sparks ever upward into the air and away from the fire.
What appears to be happening here is that these hot streams of gas bubble outwards, dragging the dusty filamentary material with them as they go. The galaxy’s magnetic field is also swept out in the process, which not only keeps the dusty tendrils bundled together but also sculpts them into their unique wreath-like shape.
Pan across the galaxy NGC 4696
Meanwhile, at the galaxy’s very center, the filaments loop and curl inwards in an vaguely spiral shape, swirling close enough around the supermassive black hole that they’re dragged into and eventually gobbled up by the black hole itself. In that regard, the black hole is once again a little like a campfire: it both consumes what’s closest to the flames while lofting other material up and out via heat and energy. Think of that the next time you warm your hands by the fire.
If you’re into galaxies and galaxy clusters or just want hold a chunk of the universe in the palm of your hand, check out Clemens Steffin’s Kickstarter effort. Steffin has created a beautiful, 3-inch (8 cm) diameter glass sphere lasered with 380,000 minute dots, each representing a galaxy in the Laniakea Supercluster, a vast skein of galaxies of which the Milky Way is a member. Peering into the sphere may just transport you into outer space!