NGC 1300: A Tale of Two Telescopes - Webb vs. Hubble

A breathtaking new image of the face-on barred spiral galaxy, NGC 1300, offers a unique perspective by comparing the infrared prowess of the James Webb Space Telescope (JWST) with the classic visible light observations from the Hubble Space Telescope (HST).

This composite image, split diagonally, highlights the distinct ways these powerful observatories capture the universe. The top left portion showcases Webb's infrared gaze, while the bottom right reveals Hubble's visible light perspective. Let's dive into what makes these views so different and what they tell us about this magnificent galaxy.

Image Credit: NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), PHANGS Team

Decoding the Colors: What Webb and Hubble Reveal

The differences in color between the two images are not just aesthetic; they are crucial to understanding the composition and processes within NGC 1300.

Gas and Dust

In Webb's high-resolution infrared images, gas and dust are rendered in striking shades of orange and red. These regions reveal finer spiral shapes with jagged edges, indicating areas that are still diffuse. Hubble's visible light images, on the other hand, show gas and dust as hazy dark brown lanes, following similar spiral patterns. While Hubble's resolution is comparable, the dust significantly obscures smaller-scale star formation.

Bright Central Spikes

Bright red diffraction spikes emanating from a galaxy's core in a Webb image can signal the presence of an active supermassive black hole. However, these spikes aren't always indicative of black holes and can also appear when extremely bright, centrally located star clusters are present. Hubble's images, with less bright galactic cores, typically lack these prominent diffraction spikes.

Older Stars

Webb's infrared capabilities allow it to peer through gas and dust, revealing a blue glow in the central regions, which signifies high concentrations of older stars. These stars emit light at shorter infrared wavelengths, hence their blue assignment. Hubble's images may show these central regions as yellower, with the older stars emitting longer visible light wavelengths, resulting in a different color interpretation.

Younger Stars

Newly formed stars appear blue in Webb's image, having cleared the gas and dust surrounding them. Stars farther from the core are more likely to be younger. Orange stars, often seen in groups, are even younger and still embedded in their dusty cocoons. Hubble captures younger stars as blue and purple, appearing more widespread, while older stars near the center are yellowish.

Star-Forming Regions

Knots of bright red and orange, particularly towards the outer edges of the spiral arms in Webb's image, denote active star formation. The mid-infrared light highlights the gas and dust crucial for these stellar nurseries. In Hubble's images, star-forming regions are clusters of bright blue and purple, or sometimes red and pink where hot stars energize nearby hydrogen gas.

Background Galaxies

Webb's view also captures distant galaxies behind NGC 1300. These appear as bright blue and pink disks, some seen edge-on, with redder galaxies indicating greater distances. Hubble shows these distant galaxies as light orange for closer ones, and deeper red for those further away.

A Deeper Understanding

By comparing these two iconic telescopes, we gain a richer and more nuanced understanding of the intricate structures and processes happening within galaxies like NGC 1300. Each wavelength of light offers a unique window into the cosmos, and together, they paint a more complete picture of the universe's wonders.