Mysterious 250 Light-Year-Wide 'Superbubble' Ripping Apart Nearby Nebula

A new image produced by the Hubble Space Telescope shows a tremendous "superbubble" ripping through a nebula, and researchers don't know yet what caused it. The 250 light-years wide and 325 light-years long "superbubble" is a striking feature in the nebula named N44, a dark starry gap against glowing hydrogen gas clouds, dark dust lanes and clusters of stars of varying ages. While NASA says that the presence of the N44 superbubble, or NGC1929 as it's officially known, is something of a mystery, scientists have a few ideas about what may have created it. One possible explanation is that stellar winds from the massive stars within the bubble are pushing away gas. The only lingering problem with this hypothesis is that the measured stellar wind velocities within the superbubble seem to be inconsistent with such a mechanism.

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Another possible explanation for the gap in the N44 nebula is that when the massive stars that fill the region reach the end of their natural lifespans, exhausting their nuclear fuel, they explode in tremendous supernovas. As these cosmic explosions shed outer layers of material from the dying stars, researchers posit that these shells of material could be spreading outwards pushing gas like a snowplow. And just as a snowplow piles up mounds of snow at the side of the road, these supernova shells could push gas and dust to the edge of the superbubble. As this material is the fuel for star production, this means that the edge of the superbubble should be a star-forming region and thus marked by younger stars.

NASA says that astronomers found in the direction of five o'clock around the N44 superbubble is its hottest region. This deep blue area is the location of intense star formation. Researchers have also observed a 5 million-year age gap between stars within the bubble and those at its edge. The N44 nebula and its superbubble structure are located with the Large Magellanic Cloud, a satellite galaxy around the Milky Way that is around 163,000 light-years away from Earth. N44 itself is located around 170,000 light-years from Earth and spans around 1,000 light-years. The nebula's glow is the result of the energization of its gas by nearby stars. This causes electrons to be stripped from atoms that make up the gas, a process called ionization. When this ionized gas cools it emits energy in the form of light.

Another Huge Void in Space

As titanic as the N44 superbubble is, it is still diminutive compared to another void in space that was discovered in Milky Way earlier this year. As Newsweek previously reported, in September astronomers including the Center for Astrophysics (CfA) researcher Alyssa Goodman announced that using 3D maps of a nearby star-forming cloud of gas, they had discovered a 500 light-year wide "void" in space. "When I was a graduate student, in the 1980s, I never, ever, dreamed that I would see real, 3D, maps of star-forming clouds. Even the closest clouds are hundreds of light-years away, so, absent Star Trek warp speed, we would never have a chance of 'flying around them' and mapping them in 3D," Goodman told Newsweek. "Instead, computers and telescopes have gotten so good that we can image these clouds with, essentially mathematics." As with the superbubble in N44, the researchers who discovered this void suggested that it was formed when massive stars within it went supernova.