NASA has recently shared a picture of the beautiful Butterfly Nebula, also known as NGC 6302. This cosmic butterfly extends its wings deep within the constellation Scorpius. 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 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.
However, 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. They discovered roughly half a dozen ‘jets’ pushing material out in a series of asymmetrical outflows. The material in the outer portions of the nebula is moving rapidly, at about 500 miles per second, while material closer to the hidden central star is expanding much more.