Astronomers have captured images of a violent and explosive star birth about 1,500 light-years from Earth, which gives new insights into stellar formation across the cosmos. Around 500 years ago, a pair of adolescent protostars had a perilously close encounter that blasted their stellar nursery apart.
Using the Atacama Large Millimetre/submillimetre Array (ALMA) telescope in Chile, astronomers have examined the widely scattered debris from this explosive event. Shortly after starting to form some 100,000 years ago, several protostars in the Orion Molecular Cloud 1 (OMC-1), a dense and active star factory about 1,500 light-years from Earth just behind the Orion Nebula, latched onto each other gravitationally and gradually drew closer.
Eventually, two of these stars either grazed each other or collided, triggering a powerful eruption that launched other nearby protostars and hundreds of giant streamers of dust and gas into interstellar space at speeds greater than 150 kilometres per second. This cataclysmic interaction released as much energy as our Sun emits over the course of 10 million years. Today, the remains of this spectacular explosion are visible from Earth.
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“What we see in this once calm stellar nursery is a cosmic version of a 4th of July fireworks display, with giant streamers rocketing off in all directions,” said John Bally from University of Colorado in the US. Groups of stars such as those in OMC-1 are born when a cloud of gas hundreds of times more massive than our Sun begins to collapse under its own gravity. In the densest regions, protostars form and begin to drift about randomly. Over time, this random motion can dampen, which allows some of the stars to fall toward a common centre of gravity, usually dominated by a particularly large protostar.
If these stars draw too close to each other before they drift away into the galaxy, violent interactions can occur. According to the researchers, such explosions are expected to be relatively short lived, with the remnants like those seen by ALMA lasting only centuries.”By destroying their parent cloud, as we see in OMC-1, such explosions may also help to regulate the pace of star formation in these giant molecular clouds,” said Bally.
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Researchers observed this feature previously with the Gemini-South telescope in Chile. These earlier images, taken in the near infrared, reveal the remarkable structure of the streamers, which extend nearly a light-year from end to end. Hints of the explosive nature of this outflow were first uncovered in 2009 with the Submillimetre Array in Hawaii.
The new ALMA data provide much greater clarity, unveiling important details about the distribution and high-velocity motion of the carbon monoxide (CO) gas inside the streamers. This helps astronomers understand the underlying force of the blast and the impact such events could have on star formation across the galaxy.The research was published in the Astrophysical Journal.