The NASA/ESA Hubble Space Telescope has captured the most detailed image yet of NGC 4696, an unusual looking galaxy with a bright core wrapped in a system of dusty, capillary-like filaments.
This Hubble image shows the elliptical galaxy NGC 4696. Image credit: NASA / ESA / Hubble / A. Fabian.
NGC 4696 is an elliptical galaxy located in the constellation of Centaurus, approximately 116 million light-years away.
Also known as ESO 322-91 and LEDA 43296, the galaxy is some 30,000 light-years across.
NGC 4696 is the largest galaxy in the Centaurus Cluster (Abell 3526), a swarm of hundreds of galaxies all sitting together.
Even if NGC 4696 keeps impressive company, it has a further distinction: the galaxy’s unique structure.
Previous observations have revealed curling filaments that stretch out from its main body and carve out a cosmic question mark in the sky, the dark tendrils encircling a brightly glowing center.
A University of Cambridge-led team of astronomers has now used Hubble observations to explore this thread-like structure in more detail.
The scientists found that each of the dusty filaments has a width of about 200 light-years, and a density some 10 times greater than the surrounding gas.
These filaments knit together and spiral inwards towards the center of NGC 4696, connecting the galaxy’s constituent gas to its core.
In fact, it seems that the galaxy’s core is actually responsible for the shape and positioning of the filaments themselves.
At the center of NGC 4696 lurks a supermassive black hole. This floods the galaxy’s inner regions with energy, heating the gas there and sending streams of heated material outwards.
It appears that these hot streams of gas bubble outwards, dragging the filamentary material with them as they go.
The galaxy’s magnetic field is also swept out with this bubbling motion, constraining and sculpting the material within the filaments.
At the very center of NGC 4696, the filaments loop and curl inwards in an intriguing spiral shape, swirling around the supermassive black hole at such a distance that they are dragged into and eventually consumed by the black hole itself.
Understanding more about filamentary galaxies such as NGC 4696 may help us to better understand why so many massive galaxies near to us in the Universe appear to be dead; rather than forming newborn stars from their vast reserves of gas and dust, they instead sit quietly, and are mostly populated with old and aging stars.
This is the case with NGC 4696. It may be that the magnetic structure flowing throughout the galaxy stops the gas from creating new stars.
