Cool gases ideal for star formation in galaxies

Astronomers have discovered that a cool cosmic environment is ideal for the creation of new stars.

A surge of warm gas from a nearby galaxy - left over from the devouring of a separate galaxy - eliminates star formation by agitating the available chilled gas, the study says.

Astronomers wanted to understand why galaxies in the local universe fall into two major categories: younger, star-forming spirals (like our own Milky Way) and older ellipticals in which fresh star making has ceased.

The new study observed galaxy NGC 3226, which occupies a transitional middle ground so getting a lead on its star formation was critical.

"We have explored big data archives from NASA and European Space Agency's space telescopes to pull together a picture of an elliptical galaxy that has undergone huge changes in its recent past due to violent collisions with its neighbours," said Philip Appleton, project scientist for the NASA Herschel Science Center at the California Institute of Technology in Pasadena.

These collisions are modifying the condition of the gas that resides in it, making it hard for the galaxy to form many stars, he added.

NGC 3226 is relatively close, just 50 million light-years away from Earth.

The data from the three telescopes finds that NGC 3226 has a very low rate of star formation.

It appears that in this case, the material falling into NGC 3226 is heating up as it collides with other galactic gas and dust, quenching star formation instead of fueling it.

As the warm gas flooding NGC 3226 cools to star-forming temperatures, the galaxy should get a second wind, the authors said.

The paper appeared on Astrophysical Journal.