Science and exploration
02/08/2022 3696 views 82 likes
The Cartwheel Galaxy, a rare ring galaxy shrouded in dust and mystery, has been revealed by the imaging capabilities of the NASA/ESA/CSA James Webb Space Telescope. The galaxy, which formed as a result of a collision between a large spiral galaxy and another smaller galaxy, has not only retained much of its spiral character, but has also undergone massive changes throughout its structure Webb’s high-precision instruments resolved individual stars and star-forming regions within the Wheel, revealing the behavior of the black hole within its galactic center. These new details provide a renewed understanding of a galaxy in the midst of a slow transformation.
Revealing details of the Cartwheel galaxy
Webb has peered into the chaos of the Cartwheel Galaxy, revealing new details about star formation and the galaxy’s central black hole. Webb’s powerful infrared gaze produced this detailed image of the Cartwheel and two smaller companion galaxies against a backdrop of many other galaxies. This image provides a new look at how the Cartwheel Galaxy has changed over billions of years.
The Cartwheel Galaxy, located about 500 million light-years away in the constellation of the Sculptor, is a rare sight. Its appearance, very similar to that of a wagon wheel, is the result of an intense event: a high-speed collision between a large spiral galaxy and a smaller galaxy not visible in this image. Collisions of galactic proportions cause a cascade of different, smaller events between the galaxies involved; the Cartwheel is no exception.
The collision most notably affected the shape and structure of the galaxy. The Cartwheel Galaxy has two rings: a bright inner ring and a colorful ring surrounding it. These two rings expand outward from the center of the collision, like ripples in a pond after a stone is thrown into it. Because of these distinctive features, astronomers call it a “ring galaxy,” a less common structure than spiral galaxies like our Milky Way.
Cartwheel Galaxy (NIRCam and MIRI)
The bright core of the galaxy hosts an active galactic nucleus, which is a supermassive black hole surrounded by an enormous amount of hot gas and dust. The brightest areas host populations of older stars, while the outer ring, which has been expanding for about 440 million years, is dominated by the formation of new stars and supernovae. As this ring expands, it enters the surrounding gas and triggers star formation.
Other telescopes, including the NASA/ESA Hubble Space Telescope, have previously examined the Cartwheel. But the dramatic galaxy has been shrouded in mystery, perhaps literally, given the amount of dust obscuring the view. Webb, with his ability to detect infrared light, now uncovers new insights into the nature of the Cartwheel.
The Near Infrared Camera (NIRCam), Webb’s primary imager, looks in the near-infrared range from 0.6 to 5 microns, seeing crucial wavelengths of light that can reveal even more stars than those observed in visible light. This is because young stars, many of which are forming in the outer ring, are less obscured by the presence of dust when viewed in infrared light. In this image, the NIRCam data are colored blue, orange and yellow. The galaxy shows many individual blue dots, which are individual stars or pockets of star formation. NIRCam also reveals the difference between the smooth shape or distribution of the oldest star populations and the dense dust in the core compared to the lumpy shapes associated with the younger star populations outside it.
Cartwheel Galaxy (MIRI)
However, learning finer details about the dust inhabiting the galaxy requires Webb’s Mid-Infrared Instrument (MIRI). MIRI data is colored red in this composite image. It reveals regions within the Cartwheel galaxy rich in hydrocarbons and other chemical compounds, as well as silica dust, like much of Earth’s dust. These regions form a series of spiral radii that essentially form the skeleton of the galaxy. These radii are evident in previous Hubble observations released in 2018, but become much more prominent in this Webb image.
Webb’s remarks underscore that the Cartwheel is in a very transitional stage. The galaxy, which was presumably a normal spiral galaxy like the Milky Way before its collision, will continue to transform. While Webb gives us a snapshot of the current state of the Chariot’s Wheel, it also provides insight into what happened to this galaxy in the past and how it will evolve in the future.
About Webb
The James Webb Space Telescope is the world’s leading space science observatory. Webb will solve the mysteries of our solar system, look beyond distant worlds around other stars, and investigate the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA and the Canadian Space Agency. ESA’s main contributions to the mission are: the NIRSpec instrument; the MIRI instrument optical bank assembly; the provision of launch services; and personnel to support mission operations. In exchange for these contributions, European scientists will get a minimum share of 15% of the total observing time, like the NASA/ESA Hubble Space Telescope.
NIRCam was built by a team from the University of Arizona and Lockheed Martin’s Advanced Technology Center.
MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European institutes (the European MIRI Consortium) in collaboration with JPL and the University of Arizona.
For more information, please contact:ESA Media Relationsmedia@esa.int
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