Array Captures Fireworks From Stellar Collision

The remnants of the collision of two young stars in the Orion system, as captured by the ALMA observatory in Chile. (ALMA (ESO/NAOJ/NRAO), J. Bally)

(CN) – The violent and explosive nature of star births has been captured in new images of a cloud of gas hundreds of times more massive than the sun, the aftermath of two heavenly bodies striking each other.

Captured by the Atacama Large Millimeter/submillimeter Array, or ALMA, the images show an active star formation factory within the constellation of Orion – roughly 1,350 light years away from Earth – in which two young stars interacted, causing streams of dust and gas to jet into space at over 90 miles per second.

“What we see in this once calm stellar nursery is a cosmic version of a Fourth of July fireworks display, with giant streamers rocketing off in all directions,” John Bally of the University of Colorado said.

Bally is the lead author of a paper published Friday in the Astrophysical Journal, which details how 500 years ago the stars either grazed each other or collided, triggering a powerful reaction that also launched other protostars into space at break-neck speeds. Today, the remains of this explosion are visible from Earth.

Photo: ALMA (ESO/NAOJ/NRAO), J. Bally

Groups of stars are born when a massive cloud of gas begins to collapse under its own gravity. In the densest regions, protostars form and begin to float along randomly. Over time, some stars begin to fall toward a common center of gravity, which is usually dominated by a massive protostar.

When protostars are drawn too close to each other before drifting away into the galaxy, violent interactions can occur.

The team says such explosions are believed to be relatively brief, the remnants of which – like those seen by ALMA – last only centuries.

“Though fleeting, protostellar explosions may be relatively common,” Bally said.

The new data will help astronomers understand how such events impact star formation across the Milky Way galaxy.

“People most often associate stellar explosions with ancient stars, like a nova eruption on the surface of a decaying star or the even more spectacular supernova death of an extremely massive star,” Bally said.

“ALMA has given us new insights into explosions on the other end of the stellar life cycle: star birth.”


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