Warm Gas Streaming from a Galaxy Stops Star Formation Cold

It turns out that when it comes to creating new stars, a cool cosmic environment is the best policy. Scientists have discovered a surge of warm gas that flowed into a nearby galaxy extinguished star formation by agitating the available chilled gas.

Astronomers have long wanted to understand why galaxies in the local universe fall into two major categories: younger, star-forming spirals-like our Milky Way-and older ellipticals, in which fresh star-making has ceased. In this case, the new galaxy that scientists have spotted occupies a transmitional middle ground.

"We have explored the fantastic potential of big data archives from NASA's Hubble Spitzer and ESA's Herschel observatory to pull together a picture of an elliptical galaxy that has undergone huge changes in its recent past due to violent collisions with its neighbors," said Philip Appleton, one of the researchers, in a news release. "These collisions are modifying not only its structure and color, but also the condition of the gas that resides in it, making it hard-at the moment-for the galaxy to form many stars."

The galaxy is called NGC3266, and is located just 50 million light-years away. Several star-studded gassy loops emanate from the galaxy, and filaments run from it and between a companion galaxy, called NGC 3227.  These streamers actually suggest that a third galaxy probably existed until NGC 3226 cannibalized it.

What's interesting is that a prominent piece of these messy leftovers extends into the core of NGC 3226. This long tail ends as a curved plume in a disk of warm hydrogen gas and a ring of dust. While adding material into galaxies usually rejuvenates them, it appears that in this case, the heated material is quenching star formation.

"We are discovering that gas does not simply funnel down into the center of a galaxy and feed the supermassive black hole known to be lurking there," said Appleton. "Rather, it gets hung up in a warm disk, shutting down star formation and probably frustrating the black hole's growth by being too turbulent at this point in time."

The findings reveal a bit more about galaxy and star formation. Not only that, but it shows how galaxies interact with one another.

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