Ghostly Cat’s Head Nebula lurks within sight of Hubble and Webb

Like a spectral form rising out of a cold mist, the Hubble and James Webb Space Telescopes have come across a hauntingly dynamic star-forming scene within the vast Carina Nebula, a diffuse star-forming region. The small, select area that was observed by both telescopes is nicknamed the Cat’s Head Nebula because of its resemblance to a cat sitting with its back toward the viewer. The ‘head’ of the cat is turned to the right, revealing a glowing eye.

The distinctive shape of the Cat’s Head Nebula has likely been sculpted over time by the intense ultraviolet radiation and winds from massive stars in the Carina Nebula. As this stellar feedback erodes the surrounding gas and dust, denser material within the feline-shaped pillar resists erosion, at least for now.

Hubble’s visible-light view shows the nebula as an opaque, dark brown pillar of dust. The cat’s glowing red eye may mark a young star that is still partially embedded in the dust. A ridge of hazy yellow seems to follow the edge of the filament’s right side. This bright rim is consistent with gas illuminated and ionised by ultraviolet radiation from nearby massive stars, potentially driving photoevaporation. This wispy outline is a sign that energetic ultraviolet light from massive, hot stars is impinging on the gas, heating it up and essentially evaporating it.

The diffuse material surrounding the pillar glows blue and cyan above, shifting to yellow, orange, and red toward the bottom. Hubble’s filters capture light emitted by oxygen, hydrogen, and sulfur, along with starlight scattered by dust. These colour variations reveal a complex mix of excited gas, dust, and stellar illumination.

Webb’s near- and mid-infrared images each offer different pieces of information to help create a more well-rounded understanding of the Cat’s Head Nebula. While the nebula’s overall structure is similar to the visible-light image, the filament becomes more transparent, and its complex surface structure becomes discernable in near-infrared light. On the cat’s left are ghostly wisps of dust and gas, delicate structures exposed to radiation from nearby massive stars.

The bright optical nebulosity visible to Hubble becomes less prominent in Webb’s near-infrared image. Instead, Webb’s near-infrared view reveals a dense scattering of stars that appear blue and yellow in this colour-composite image. Even in infrared light, some stars are still enshrouded in dust to various degrees. The cat’s eye remains conspicuous, while a faint jet-like feature near the cat’s belly could indicate an outflow associated with a young star.The cat’s eye is a more obvious example of an embedded star, while a faint jet protruding from the cat’s belly hints that a young star is located nearby, perhaps within the cat or externally just to its right. 

In mid-infrared light, emission from warm dust and carbon-based molecules outlines intricate structures within the nebula. The filament’s bluish and greenish colours highlight emission that includes polycyclic aromatic hydrocarbons (PAHs), carbon-based molecules excited by starlight. These variations in colour and brightness may reflect changes in PAH emission, dust continuum, and local irradiation, rather than temperature alone. Delicate globules and strands to the pillar’s left are particularly evident in this mid-infrared view.

To the right of the pillar, a bright light source appears yellow in the mid-infrared image. It lies against reddish emission from surrounding material. A narrow filament appears to cross the source, although the image alone cannot establish whether the two are physically related.

Though the Cat’s Head Nebula is a temporary scene that will eventually disperse, the region is packed with information. Hubble and Webb’s complementary views of the Cat’s Head Nebula are helping astronomers learn more about the elusive, chaotic, and complex process known as star formation.

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The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Webb is the largest, most powerful telescope ever launched into space. Under an international collaboration agreement, ESA provided the telescope’s launch service, using the Ariane 5 launch vehicle. Working with partners, ESA was responsible for the development and qualification of Ariane 5 adaptations for the Webb mission and for the procurement of the launch service by Arianespace. ESA also provided the workhorse spectrograph NIRSpec and 50% of the mid-infrared instrument MIRI, which was designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership with JPL and the University of Arizona.

Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA).

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