Combined power of the NASA’s Hubble and Webb space telescopes (IMAGE)
Caption
This diagram illustrates the combined power of the NASA’s Hubble and Webb space telescopes in nailing down precise distances to a special class of variable star that is used in calibrating the expansion rate of the universe. These Cepheid variable stars are seen in crowded star fields. Light contamination from surrounding stars may make the measurement of the brightness of a Cepheid less precise. Webb’s sharper infrared vision allows for a Cepheid target to be more clearly isolated from surrounding stars, as seen in the right side of the diagram. The Webb data confirms the accuracy of 30 years of Hubble observations of Cepheids that were critical in establishing the bottom rung of the cosmic distance ladder for measuring the universe’s expansion rate. At the left, NGC 5584 is seen in a composite image from Webb’s NIRCam (Near-Infrared Camera) and Hubble’s Wide Field Camera 3.
Credit
Image Credit: NASA, ESA, A. Riess (STScI), W. Yuan (STScI).
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