Old galaxy seen making new stars

Images from the Hubble Space Telescope show the core of an elliptical galaxy known as NGC 4150, thought to be well past its period of star formation, surrounded by streamers of dust, gas and young, blue stars considerably less than 1 billion years old, SPACE.com reported Tuesday.

Scientists say the finding suggests elliptical galaxies can still have some youthful vigor left, possibly through encounters with smaller galaxies, and that the star birth in NGC 4150 may have been kicked off by a collision and merger with a dwarf galaxy.

"Elliptical galaxies were thought to have made all of their stars billions of years ago," astronomer Mark Crockett of the University of Oxford says. "They had consumed all their gas to make new stars. Now we are finding evidence of star birth in many elliptical galaxies, fueled mostly by cannibalizing smaller galaxies."

Astronomers' theories on how these galaxies form may change with the new findings, he said

"These observations support the theory that galaxies built themselves up over billions of years by collisions with dwarf galaxies," Crockett says. "NGC 4150 is a dramatic example in our galactic backyard of a common occurrence in the early universe."

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