UNITED STATES: A new understanding of star creation and the galaxy’s central black hole has been achieved as NASA’s James Webb Space Telescope gaze into the turmoil of the Cartwheel Galaxy. The Cartwheel and two smaller partner galaxies were captured in this finely detailed image by Webb’s strong infrared stare against a background of numerous other galaxies.
The Cartwheel Galaxy has altered over billions of years, and this image offers a fresh perspective on those changes. It isn’t easy to see the Cartwheel Galaxy, which is 500 million light-years away in the Sculptor constellation. This dramatic event—a high-speed collision between an enormous spiral galaxy and a smaller galaxy that isn’t seen in this image—gave it the look of a wagon wheel. The Cartwheel is one of several other, more minor occurrences that result from collisions of galactic scale between the galaxies involved.
Most significantly, the galaxy’s structure and appearance were impacted by the collision. The Cartwheel Galaxy has two rings: a vivid outer ring and a bright inner ring. Similar to the ripples in a pond when a stone is thrown into it, these two rings spread outward from the point of collision because of these distinguishing characteristics, astronomers refer to this galaxy as a “ring galaxy,” a less frequent structure than spiral galaxies like the Milky Way.
Huge young star clusters are seen in the brightest regions of the core, which also includes an enormous amount of hot material. On the other side, star formation and supernovae predominate in the outer ring, which has been growing for nearly 440 million years. As it grows, this ring collides with the surrounding gas, causing star formation.
The Hubble Space Telescope and other telescopes have previously studied the Cartwheel. Due to the amount of dust obscuring the view, the mysterious galaxy has been wrapped in mystery. Now that Webb can detect infrared light, we can better understand the nature of the Cartwheel.
The Near-Infrared Camera (NIRCam), the main imager on Webb, scans the sky between 0.6 and 5 microns in the near-infrared, picking up essential light wavelengths that can show even more stars than those seen in the visible spectrum. This is because when young stars are detected in infrared light, many of which are forming in the outer ring, they are less veiled by the presence of dust. NIRCam data are tinted blue, orange, and yellow in this image.
Numerous blue dots that make up the galaxy are individual stars or star formation regions. The smooth distribution or shape of the older star populations and dense dust in the core contrasts with the clumpy shapes linked to the younger star populations outside of it, as shown by NIRCam.
But to understand the galaxy’s dust in greater detail, Webb’s Mid-Infrared Instrument is needed (MIRI).
In this composite image, MIRI data is highlighted in red. It indicates areas of the Cartwheel Galaxy that are abundant in silicate dust, which is similar to much of the dust on Earth, as well as hydrocarbons and other chemical substances. These regions combine to create a web of spiraling spokes that serve as the galaxy’s skeleton. These spokes may be seen in earlier Hubble views published in 2018, but they stand out much more in this Webb image.
Webb’s observations confirm that the Cartwheel is going through a very fleeting phase. Before the collision, the galaxy was probably a typical spiral galaxy like the Milky Way, which will probably continue to change. While Webb provides a glimpse of the Cartwheel’s current situation, it also sheds light on the galaxy’s historical events and potential future developments.