Scientists released the latest images of Triumph of NASA’s James Webb Space Telescope. The last version documents the Cartwheel galaxy, which lies about 500 million light-years from our planet and is aptly named for its wheel-like appearance, complete with a central hub, tire, and even wavy, fluorescent spokes. The Webb also recorded two smaller companion galaxies alongside Cartwheel.
The new images follow NASA’s July 12 unveiling of five initial scenes captured by the Webb Telescope, the most powerful space observatory built to date. Since their launch on December 25, Webb’s 18 gold hexagonal mirrors have lined up to capture other targets in space, although not all of the images have been released. Snapshots included the South Ring Nebulawhich looks like a soap bubble expanding from a dead star, and the striking Carina Nebulacomposed of swirling dust similar to jagged cliffs.
Astronomers have studied the Cartwheel galaxy for decades. Initially, it was inspected from two ground-based observatories in Australia, first the British Schmidt Telescope and later the Anglo-Australian Telescope. But he is best known from the The Hubble Space Telescopewho images produced in the 1990s with more details on the composition of the galaxy. And just as the Webb, in July, revealed the presence of even more distant galaxies hiding from our viewhis Cartwheel photographs magnified the detailed star formation in the rings of the galaxy and the dozens of other star systems beyond.
Cartwheel’s appearance stems from a collision of two galaxies that occurred hundreds of millions of years ago. “We guess the cartwheel probably started to look like the Milky Way, and then this other galaxy moved on,” said Marcia Rieke, main finder of the near-infrared camera, or NIR Cam, one of the scientific instruments of the Webb telescope. The smaller galaxy, however, rather than get stuck in the great spiral it entered, continued, moving away from the larger one. It is not visible in the image released by NASA.
Galactic collisions are not uncommon in deep space, though it is rare that they result in such a perfect shape that arouses human curiosity. Kirk Borne, who was the principal investigator of the Hubble Cartwheel observation but was not involved in the Webb, said the odd shape of the galaxy, which coincidentally formed during the merger, motivated astronomers to study it for decades.
Because a smaller galaxy crashed into a larger one – and directly in the middle – it disrupted the shape of each galaxy less, and both were relatively able to retain their individuality. “What changed the shape of Cartwheel was the influence of the gravitational field of this other galaxy that changed the orbits of the stars in the original Cartwheel galaxy,” Dr Rieke said.
Dr. Borne, who has studied other galaxy collisions, described the smaller galaxy as a bullet that went through the large one. After the sighting of the cosmic object in the 1990s, scientists noticed a trail of hydrogen gas following the smaller galaxy, which Dr Borne called the “smoking gun”, indicating that it had continued to move after creating Cartwheel’s new formation.
Already 1.5 times larger than the Milky Way, Cartwheel is still expanding, and new stars are forming both inside its outer ring and at its edge. However, there is no concrete answer on how big Cartwheel will become, when it will stop growing, or what shape it will take when it does.
Cartwheel images were already in hand on July 12, although they weren’t made available to the public until this week. They have been filtered for make them more visually accessible, highlighting the bright blue-hued young stars and the red-toned molecules of older stars and the space dust floating between the rings. Although colorful, Joseph DePasquale, lead science visuals developer at the Space Telescope Science Institute, which runs the Webb and Hubble spacecraft, pointed out that stars and dust are actually detected as infrared light instead of color.
The new technology to detect this light in such detail is what sets Webb’s images apart from those made by Hubble and the Anglo-Australian Telescope. While Hubble had some ability to record light in the infrared spectrum, Webb is more advanced and creates more vivid images. The NIRCam, for example, which was built by about 25 people working with Dr. Rieke over 11 years, distinguishes the infrared colors of stars, which are invisible to the human eye, from each other.
When Hubble captured Cartwheel in the 1990s, the galaxy’s ‘beams’ were obscured by light-scattering clouds of gas, making it difficult to see the thousands of stars forming within . Now, because the Webb can study mid-infrared and near-infrared wavelengths of light, it’s able to filter out space dust. This helps confirm some of the Cartwheel makeup theories that have been formed using Hubble technology and uncover new insights, such as the absence of star formation in certain areas between the rays of the wheel.
“I think the combination of the two telescopes, far from making either of them obsolete, it actually just enhances the advantages and the power of Hubble because now we can make these comparisons,” Dr Borne said.
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