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Remember the Pillars of Creation? Since the Hubble Space Telescope captured this spectacular photograph in 1995, it has appeared on posters, T-shirts and screen savers. Although everybody seems to be familiar with the pillars, the details of how they formed have been unclear. A computer simulation may have finally solved the mystery. Using the physics of gas flows, Cardiff University astronomer Scott Balfour and his colleagues have reproduced the famous pillar structures almost exactly.
The trio of gas columns, located inside the Milky Way's Eagle Nebula, earned its moniker because the columns are factories for creating stars. The pillars themselves are the product of a massive nearby O-type star that sculpted the gas with its powerful winds. O-stars are the universe's largest, hottest stars and live short lives that wreak havoc on their environments. Their intense radiation heats up surrounding gas to form expanding bubbles. And according to the new simulation, which spans 1.6 million years, columns with all the features of the Pillars of Creation naturally form along the outer rim of such bubbles as they expand and rip at the edges.
The simulation, which Balfour presented in June at the British Royal Astronomical Society's National Astronomy Meeting, also showed that O-stars have unexpected effects on star formation. Previous studies have suggested that O-stars initiate the creation of stars, which can often be found in their vicinity. The simulation, however, shows that the bubbles around O-stars often destroy star-forming clouds. In other cases, they compress surrounding gas to initiate the birth of stars sooner than they would have arisen otherwise, causing them to be smaller. “We were very surprised by that,” Balfour says. Simulations by James Edward Dale, an astronomer at the University Observatory in Munich, also question whether O-stars really trigger star formation. Says Dale, “I find that the triggering is much less important than the destructive effects, which looks to be true in Balfour's simulations, too.” It's a universal truth: destruction and creation go hand in hand.