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Uncrowding Cepheids in the Near Infrared

Graphic titled “Uncrowding Cepheids in the Near-Infrared” includes a Hubble and Webb image of spiral galaxy NGC 5584; a diagram comparing the resolution of the Webb data to that of the Hubble data; and a comparison of a Webb NIRCam image detail to the Hubble WFC3-IR image detail of the same region.

This diagram illustrates the combined power of the 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.

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About the Object

  • R.A. Position
    R.A. PositionRight ascension – analogous to longitude – is one component of an object's position.
    14:22:23.76
  • Dec. Position
    Dec. PositionDeclination – analogous to latitude – is one component of an object's position.
    00:23:15.61
  • Constellation
    ConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.
    Virgo
  • Distance
    DistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.
    About 72 million light-years (22 million parsecs)
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    NGC 5584
  • Object Description
    Object DescriptionThe type of astronomical object.
    Spiral galaxy, cepheid host galaxy
  • Release Date
    September 12, 2023
  • Credit
    NASA, ESA, CSA, Adam Riess (JHU, STScI); Illustration: Joyce Kang (STScI)

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Details

Last Updated
Aug 28, 2025
Contact
Media

Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov

Science Credit

NASA, ESA, CSA, Adam Riess (JHU, STScI)

Illustration Credit

Joyce Kang (STScI)

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