Gemini South Observatory Marks 25 Years with New Butterfly Nebula Image

The Gemini South Observatory, an 8.1-meter optical/infrared telescope located on Cerro Pachón in the Chilean Andes, recently marked its 25th anniversary since achieving First Light in November 2000. The facility, operated by the National Science Foundation (NSF) and managed by NSF NOIRLab, commemorated the milestone by holding the Gemini First Light Anniversary Image Contest.

Participants in the contest were students from the observatory's host communities in both Chile and Hawaii, who voted to select the imaging target. Their choice was the Butterfly Nebula, cataloged as NGC 6302. The new image, captured by Gemini South in late 2025, reveals the dynamic gaseous outflows driven by the nebula’s intensely hot central star. The color scheme used in the visualization differentiates chemical elements: red tones indicate ionized hydrogen gas, while bright blue traces ionized oxygen.

This representation contrasts with a 2009 observation from the Hubble Space Telescope, where the red channel depicted ionized nitrogen. The bipolar planetary nebula spans over two light-years and is situated between 2,500 and 3,800 light-years away in the constellation Scorpius. It formed from the expelled outer layers of a dying, intermediate-mass star that shed its material approximately 2,000 years ago.

The formation involved an initial slow expansion from the star’s equator, creating a dark equatorial disk that now appears as a central obscuring band. This was followed by a much faster stellar wind, moving at speeds exceeding three million kilometers per hour, which perpendicularly sculpted the expelled gas into the structure’s complex, wing-like features. At the core of NGC 6302 is a white dwarf star, one of the hottest known stellar remnants, with a surface temperature surpassing 250,000 degrees Celsius and a current mass of approximately 0.64 solar masses.

The intense ultraviolet radiation from this remnant ionizes the surrounding gas, causing the nebula to emit visible light. The study of planetary nebulae, a phase lasting about 20,000 years, offers vital understanding into stellar evolution and the cosmic recycling of elements. The successful imaging campaign honors Gemini South’s operational legacy and aims to engage aspiring astronomers within the host communities, alongside the work conducted by its twin, Gemini North in Hawaii.