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A Sample of Galaxy Disks (NIRCam)

Two mosaics of edge-on disk galaxies observed by the James Webb Space Telescope. Each mosaic has eight images, split in two rows. The mosaic at the top is titled “thin and thick disk galaxies.” The mosaic at the bottom is titled “thick disk only galaxies.” Each disk galaxy is centered within a square frame and lies against the black background of space. They appear as thin lines with a slight bulge in their centers. A few of the galaxies are horizontal or vertical, but many are angled diagonally. The thin and thick disk galaxies are overall whiter and brighter compared to the thick disk only galaxies, which are fainter and brown-orange. Text in the bottom right of each box lists the galaxy’s redshift. From left to right, the first row of the top mosaic reads z =0.12; z = 0.25; z = 0.45; and z = 0.72. The second row reads z = 0.21; z = 0.38; z =0.65; and z = 0.73. The top row of the bottom mosaic reads z = 0.73, z = 0.94; z = 1.25; and z = 2.63. The bottom row reads z = 0.91; z = 1.03; z = 2.13; and z = 3.01.

Present-day disk galaxies often contain a thick, star-filled outer disk and an embedded thin disk of stars. Three major theoretical scenarios have been proposed by astronomers to explain how this dual-disk structure comes to be. Using archival data from the James Webb Space Telescope, a team of astronomers is closer to understanding disk galaxies’ origins, and the stellar thick- and thin-disk formation process. The team carefully identified, visually verified, and analyzed a statistical sample of more than 100 edge-on disk galaxies at various periods — up to 11 billion years ago (or approximately 2.8 billion years after the big bang). The results of their analysis suggest that galaxies form a thick disk first, followed by a thin disk. The timing of this process depends on a galaxy’s mass: high-mass, single-disk galaxies transitioned to two-disk structures around 8 billion years ago, while low-mass, single-disk galaxies formed their thin disks about 4 billion years ago.

About the Data

  • Data Description
    Data DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
    Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.

    This image was created with Webb data from proposals: 1180 (D. Eisenstein), 1895 (P. Oesch), 2079 (S. Finkelstein), 1181 (Eisenstein), 2514 (C. Williams), 3577 (E. Egami), 1345 (S. Finkelstein), and 1837 (J. Dunlop). Image Processing: Alyssa Pagan (STScI).

  • Instrument
    InstrumentThe science instrument used to produce the data.
    NIRCam
  • Filters
    FiltersThe camera filters that were used in the science observations.
    These images are a composite of separate exposures acquired by the James Webb Space Telescope using the NIRCam instrument. Several filters were used to sample specific wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter.
  • Object Description
    Object DescriptionThe type of astronomical object.
    Thick and Thin Spiral Galaxy Disks
  • Release Date
    June 26, 2025
  • Science Release
    NASA’s Webb Digs into Structural Origins of Disk Galaxies
    Read the release
  • Credit
    Image: NASA, ESA, CSA, STScI, Takafumi Tsukui (ANU)

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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

Image Credit

NASA, ESA, CSA, STScI, Takafumi Tsukui (ANU)

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