In 2015 NASA celebrated Hubble Space Telescope25th year in orbit, releasing one of the most stunning images to date – the colorful star cluster in the constellation Carinae known as Westerlund 2. However, a lot can change in a decade. In January 2023 HST observational capabilities were captured when the mighty James Webb Space Telescope photographed the same star cluster. Although the HST is still a powerful piece of equipment, European Space Agency decided to showcase the technological achievements of its successor, ending 2025 with a new, even more detailed look at Westerlund 2.
The billowing, brightly imaged feature, located 20,000 light-years from Earth, was imaged using JWST's Near Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). Westerlund 2 is estimated to be between 6 and 13 light-years wide and contains some of the hottest, brightest and most massive stars in the galaxy. To fully appreciate the difference between what HST and JWST can see in space, ESA also loaded the slider tool to allow viewers to switch between both images of Westerlund 2. While all the brightest stars were visible in the 2015 image, the new view shows hundreds of additional, fainter stars in the background.
Transition video: Webb and Hubble views of Westerlund 2
The young stellar objects Westerlund 2 emit powerful waves of radiation in all directions, twisting and entangling the large clouds of gas that surround them. While the closer, brighter stars immediately stand out from their companions, hundreds of tiny points of light reveal some of their younger siblings. Around them, thicker plumes of red and orange gas also mix with thinner blue and pink filaments, depicting a dynamic and very active stellar nursery.
JWST's latest look at Westerlund 2 is more than just a pretty picture. The data also includes the total number of brown dwarf stars in the nebula, some of which are 10 times the mass of Jupiter. Astronomers can now begin to study how the disks surrounding these stellar objects form over time, and how planets end up in such huge star clusters.
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