A closeup of Hubble's image of a spiral galaxy in Coma shows the effects of strong ram pressure on the leading side of the disc. Credit: NASA/ESA/Roberto Colombari


Cosmic winds often blow through galaxies, ridding them of their interstellar material and stopping star formation dead in its tracks.

Yale astronomer Jeffrey Kenney has been looking at Hubble Space Telescope images to determine how cosmic wind erodes the gas and dust at the leading edge of a spiral galaxy in the Coma cluster, about 300 million lightyears from Earth.

In the case of this particular galaxy, cosmic wind, or ram pressure, is caused by the galaxy’s orbit through hot gas in its cluster.

Through his study, Kenney has found a series of dust formations on the galaxy’s disc edge.

“On the leading side of the galaxy, all the gas and dust appears to be piled up in one long ridge, or dust front.

But you see remarkable, fine scale structure in the dust front,” he says.

“There are head-tail filaments protruding from the dust front.

We think these are caused by dense gas clouds becoming separated from lower density gas.”

Cosmic wind is able to push and blow low-density gas and dust clouds, but not those of higher density.

This causes denser gas clouds to be left behind as the cosmic winds blow lower-density clouds across the galaxy.

But Kenney’s study has suggested that high and low-density clouds are bound together, potentially by magnetic fields.

“The evidence for this is that dust filaments in the HST (Hubble Space Telescope) image look like taffy being stretched out,” Kenney says.

“We’re seeing this decoupling, clearly, for the first time.”

Hubble images of the spiral galaxy were first seen by Kenney two years ago.

The telescope captured one of its most famous photos of the Eagle Nebula, named ‘Pillars of Creation’, in the 1990s and these new filaments discovered by Kenney are similar, except 1,000 times larger.

The pillars are the denser material left behind as cosmic winds blow the less dense material away.


In both cases, the pillars are hosting the final generation of stars being formed in these galaxies.