Cosmic Winds and Stars: The Process Behind Why Stars Aren't Born

Stars are not born, in some cases--because hugely huffy cosmic winds sweep interstellar material throughout a galaxy. While astronomers have known this, now they have a better idea of how it happens, said researchers from Yale University recently in the Astronomical Journal.

The research looked at how the cosmic wind erodes gas and dust at the galaxy's leading edge. The galaxy's orbital motion, passing through hot gas in the cluster, stirs up this wind, or ram pressure. Yale astronomer Jeffrey Kenney detected intricate dust formations there at the edge, where cosmic wind begins to channel through the galaxy, a release noted.

"There are head-tail filaments protruding from the dust front," said Kenney in the release. "We think these are caused by dense gas clouds becoming separated from lower density gas."

Basically, while cosmic wind can push around interstellar gas and dust in low-density clouds, it cannot handle very dense clouds. Dense gas lumps in the wind begin to separate from nearby lower-density gas--the latter is blown downstream. What happens next is that the high and low-density lumps partially stay together, probably linked by magnetic fields, a release said.

Kenney based his analysis on Hubble Space Telescope (HST) images of a Coma cluster spiral galaxy about 300 million light years from Earth. The cluster is the nearest of its kind to our solar system. Dust filaments in the image "look like taffy being stretched out," said Kenney in the release. "We're seeing this decoupling, clearly, for the first time."

If gas is removed from an area by the wind, stars and planets cannot be created. In both the Eagle Nebula and the Coma galaxy, intense pressure arises--from intense radiation in the first, and orbital motion through hot gas in the second. While new stars are born there, they are likely the last generation of stars to form there, according to the release.

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