The James Webb Space Telescope (JWST) has captured an unprecedentedly detailed view of the Butterfly Nebula (NGC 6302), located approximately 3,400 light-years away in the constellation Scorpius. This celestial object, representing the late stages of a star's life, is now providing profound insights into stellar evolution and the formation of planetary systems.
Utilizing its Mid-Infrared Instrument (MIRI), JWST has successfully penetrated the dense dust surrounding the nebula's central region, enabling the first direct observation of its obscured central star. This white dwarf is radiating at temperatures exceeding 220,000 Kelvin (approximately 395,000°F), making it one of the hottest known central stars in a planetary nebula within our galaxy. JWST's sensitivity also detected a previously unseen dust cloud, heated by this star, which now glows brightly in mid-infrared wavelengths.
The observations revealed a torus, a doughnut-shaped structure of crystalline silicates, including quartz, encircling the central star. This torus plays a crucial role in shaping the nebula's distinctive butterfly-like appearance by channeling the star's outflowing material. Within this complex structure, JWST identified nearly 200 distinct spectral lines, offering valuable information about the nebula's atomic and molecular composition.
A significant discovery is the presence of polycyclic aromatic hydrocarbons (PAHs), carbon-based molecules commonly found in terrestrial smoke and exhaust. Their detection within the oxygen-rich environment of the Butterfly Nebula is notable, potentially marking the first instance of PAHs forming in such a setting. Researchers suggest these molecules may arise from interactions between the central star's powerful stellar winds and the surrounding gas. This finding offers a critical glimpse into the processes governing PAH formation and their potential role in cosmic chemistry.
Furthermore, JWST data indicates that the dust grains within the torus are larger than typical interstellar dust, with some reaching sizes of a millionth of a meter, suggesting a prolonged period of growth possibly accelerated by the intense energy from the central star. The presence of both crystalline silicates and irregularly shaped dust grains underscores the diverse conditions in cosmic dust formation, representing a significant step in understanding how the fundamental materials for rocky planets coalesce. These groundbreaking discoveries have been published in the journal Monthly Notices of the Royal Astronomical Society.