Tag : Nebula

Washington: Planetary nebulae form when red giant stars expel their outermost layers as they run out of helium fuel, becoming hot, dense white dwarf stars that are roughly the size of Earth. The material that was shed, enriched in carbon, forms dazzling patterns as it is blown gently into the interstellar medium. Most planetary nebulae are roughly circular, but a few have an hourglass or wing-like shape, like the aptly named 'Butterfly Nebula'. These shapes are likely formed by the gravitational tug of a second star orbiting the nebula's 'parent' star, causing the material to expand into a pair of nebular lobes, or 'wings'. Like an expanding balloon, the wings grow over time without changing their original shape. Yet new research shows that something is amiss in the Butterfly Nebula. When a team led by astronomers at the University of Washington compared two exposures of the Butterfly Nebula taken by the Hubble Space Telescope in 2009 and 2020, they saw dramatic changes in the material within the wings. As they will report on Jan. 12 at the 241st meeting of the American Astronomical Society in Seattle, powerful winds are driving complex alterations of material within the nebula's wings. They want to understand how such activity is possible from what should be a 'sputtering, largely moribund star with no remaining fuel'. "The Butterfly Nebula is extreme for the mass, speed and complexity of its ejections from its central star, whose temperature is more than 200 times hotter than the sun yet is just slightly larger than the Earth," said team leader Bruce Balick, a UW professor emeritus of astronomy, adding, "I've been comparing Hubble images for years and I've never seen anything quite like it." The team compared high-quality Hubble ...