Hubble and Webb Examine the Cat’s Head Nebula in Carina

What does Webb reveal in infrared?

Near-infrared light lies just beyond the visible spectrum. It makes the filament more transparent while leaving its overall shape recognizable. Webb’s image also resolves its complex surface and ghostly wisps of dust and gas on the cat’s left, structures exposed to radiation from nearby massive stars.

Webb’s mid-infrared image records longer wavelengths that trace warm dust and carbon-based molecules, outlining intricate structures within the nebula.

Optical nebulosity prominent in Hubble’s view becomes less prominent in Webb’s near-infrared image. A dense scattering of blue and yellow stars appears instead in the color composite, although some remain veiled by dust to varying degrees.

Bluish and greenish areas in the mid-infrared view include emission from polycyclic aromatic hydrocarbons (large carbon-based molecules), or PAHs. The colors and brightness may reflect changes in PAH emission, dust continuum (smooth light from dust) and local irradiation (radiation reaching a particular area), rather than temperature alone.

In that mid-infrared view, delicate globules (small, compact knots) and strands stand out on the pillar’s left.

What do the eye and jet-like feature show?

The cat’s eye remains conspicuous and provides a clearer example of an embedded star. Near the cat’s belly, a faint jet-like feature could indicate an outflow associated with a young star, meaning gas ejected by that star.

The feature suggests a young star may lie nearby, either within the cat’s outline or just outside its right edge.

What remains uncertain?

Webb’s mid-infrared image also shows a bright source to the right of the pillar, appearing yellow against reddish emission from surrounding material. A narrow filament appears to cross it, but the image alone cannot establish whether the source and filament are physically related.

The Cat’s Head is a temporary scene that will eventually disperse. Even so, the region offers abundant information for studying star formation, the complex process by which new stars emerge within clouds of gas and dust. Neither instrument supplies the entire picture, because each wavelength emphasizes different matter and physical conditions.

How do the telescopes fit together?

Hubble is a project of international cooperation between the European Space Agency (ESA) and NASA. Webb is an international partnership among NASA, ESA and the Canadian Space Agency (CSA).

ESA describes Webb as "the largest, most powerful telescope ever launched into space." The agency provided Webb’s launch service using the Ariane 5 launch vehicle, while Arianespace procured that service. ESA and its partners developed and qualified the Ariane 5 adaptations required for the Webb mission.

ESA also provided the workhorse NIRSpec spectrograph (an instrument that separates light into wavelengths) and 50% of the mid-infrared MIRI instrument. The MIRI European Consortium, a group of nationally funded European institutes, designed and built MIRI in partnership with JPL and the University of Arizona.

Placed side by side, the two sets of images show how radiation, dust and embedded stars interact within one small part of the larger Carina Nebula.