Astronomers have expanded their understanding of how the Butterfly Nebula acquired its distinctive form, based on observations summarized by a major university press office.
Most planetary nebulae tend to be circular, but a few take on elongated shapes reminiscent of hourglasses or wings. The Butterfly Nebula stands out as a striking example. The prevailing interpretation has long attributed its shape to the gravitational influence of a second star that orbits the central star, directing expelled material into two lobes that resemble wings. Over time these lobes were thought to grow without altering their basic geometry.
New research challenges that traditional view. Scientists compared archival images from the Hubble Space Telescope captured in 2009 with newer data from 2020 and identified dramatic changes inside the wing regions. This finding suggests a more dynamic interior than previously believed, with ongoing activity reshaping the nebula from within. Attribution: University of Washington press service.
The study highlights the Butterfly Nebula as an extreme laboratory for mass, velocity, and the complexity of eruptive events driven by a central star that is immensely hot yet only slightly larger than Earth in overall size. The team leader described the central engine as astonishingly energetic, driving rapid, high-energy outflows that challenge simple explanations.
Researchers counted about six distinct jets that trace back roughly two millennia, continuing to shift and evolve over time. These jets carry material outward along asymmetrical channels, creating a complex network of streams. Outer regions of the nebula show material racing away at tens of hundreds of kilometers per second, while matter near the heart moves more leisurely by roughly a factor of ten. The intersections of these jet streams seed intricate, seemingly random patterns that weave through the wings as they grow.
Scientists note that such a rapidly changing interior is not easily reconciled with current models of how planetary nebulae form and mature. A dust-enshrouded star at the core may merge with a companion or siphon material from a nearby neighbor, generating tangled magnetic fields and a family of jets that sculpt the surrounding gas. Preparations are underway to observe the nebula with the James Webb Space Telescope, aiming to provide a clearer picture of the forces shaping this unusually active interior. Attribution: University of Washington press service.