The NASA/ESA Hubble Space Telescope has unveiled a striking image of Kohoutek 4-55, a planetary nebula 4,600 light-years away in the constellation Cygnus, showcasing vibrant clouds of ionized gas expelled by a dying star. Released in April 2025, the image marks the final work of Hubble’s Wide Field and Planetary Camera 2 (WFPC2), capturing the nebula’s glowing layers just days before the instrument’s retirement in 2009.
Kohoutek 4-55, part of the Milky Way, displays a star’s dramatic end as it exhausts its fuel. After shedding its outer layers as a red giant, the star’s core contracts, triggering a brief burst of fusion that emits ultraviolet light. This light ionizes surrounding gas clouds, creating a vivid display: nitrogen glows red and orange, hydrogen green, and oxygen blue.
The nebula’s structure, with a faint outer layer, a bright inner ring, and a broad nitrogen halo, is rare among planetary nebulae, which number about 20,000 in our galaxy, per NASA estimates. This luminous phase will fade in tens of thousands of years, leaving a dim white dwarf.
The image, processed with advanced techniques, highlights WFPC2’s legacy. Installed in 1993 to correct Hubble’s initial optical flaws, WFPC2 captured iconic views, including the Pillars of Creation, over 16 years. Data for Kohoutek 4-55 was collected 10 days before astronauts replaced WFPC2 with Wide Field Camera 3 during Hubble’s last servicing mission in May 2009. The European Space Agency notes that such nebulae offer clues about stellar evolution, informing models of our sun’s future in 5 billion years.
Kohoutek 4-55’s multi-layered form intrigues astronomers, as most planetary nebulae are simpler shells or bipolar structures. The nebula’s vivid colors result from specific wavelengths emitted by ionized elements, a process detailed by the Space Telescope Science Institute. Hubble’s ability to resolve these details has advanced understanding of stellar lifecycles, critical for studying galactic chemistry.
This final WFPC2 image underscores Hubble’s enduring impact, with over 1.5 million observations since its 1990 launch. The telescope continues to operate, capturing data that shapes astrophysics, while images like Kohoutek 4-55 inspire public awe at the universe’s beauty.
