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Draco Dwarf Spheroidal

At left is the Digitized Sky Survey view of the Draco dwarf galaxy. Many yellow, blue-white, and white stars are dispersed across the black background of space. They vary in shape and size, though most resemble small, circular points of light. Larger stars, some with four diffraction spikes, are scattered infrequently across the field of view. A thin, light brown oval highlights the area of interest, which contains two small white squares in its center. The area of each square is magnified at right, showing views captured by the Hubble Space Telescope. The top right square reveals a black patch of space with many small points of light and a large, four-point diffraction spike toward the left. The bottom right square shows a black patch of space filled with small points of light, some with diffraction spikes.

A team of astronomers analyzed observations by NASA's Hubble Space Telescope taken over a span of 18 years to measure the dynamic motions of stars within the Draco dwarf galaxy. The telescope's extensive baseline and data archive enabled the team to build the most accurate three-dimensional map of the stars' movements within the system. These improved measurements are helping to shed "light" on the mysterious qualities and behavior of dark matter, the universe's invisible "glue."

 

About the Object

  • R.A. Position
    R.A. PositionRight ascension – analogous to longitude – is one component of an object's position.
    17:20:12.4
  • Dec. Position
    Dec. PositionDeclination – analogous to latitude – is one component of an object's position.
    +57:54:55
  • Constellation
    ConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.
    Draco
  • 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.
    260,000 light-years
  • Dimensions
    DimensionsThe physical size of the object or the apparent angle it subtends on the sky.
    Wide field image is 1 degree across (about 4,500 light-years)Inset images are about 3 arcmin across (about 226 light-years)

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.

    The HST observations include those from program 12966 (R. van der Marel) and program 16737 (S.T. Sohn). Image Processing: Joseph DePasquale (STScI)

  • Instrument
    InstrumentThe science instrument used to produce the data.
    WFC3, ACS
  • Exposure Dates
    Exposure DatesThe date(s) that the telescope made its observations and the total exposure time.
    October 2013, October 2022
  • Filters
    FiltersThe camera filters that were used in the science observations.
    F606W, F814W
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    Draco Dwarf Spheroidal
  • Object Description
    Object DescriptionThe type of astronomical object.
    Dwarf spheroidal galaxy
  • Release Date
    July 11, 2024
  • Science Release
    NASA’s Hubble Traces Dark Matter in Dwarf Galaxy Using Stellar Motions
    Read the release
  • Credits
    NASA, ESA, Eduardo Vitral, Roeland van der Marel, and Sangmo Tony Sohn (STScI), DSS; Image processing: Joseph DePasquale (STScI)

Downloads

  • Full Res (For Display), 5174 × 3513
    png (36.15 MB)
  • Full Res (For Print), 5174 × 3513
    tif (44.8 MB)
  • 2000 × 1358
    jpg (1.45 MB)
  • Unannotated Full Res (For Display), 5174 × 3513
    png (36.27 MB)
  • Unannotated Full Res (For Print), 5174 × 3513
    tif (45.13 MB)
  • Unannotated, 2000 × 1358
    jpg (1.47 MB)
  • DSS Wide Field - Full Res (For Display), 3522 × 3520
    png (25.85 MB)
  • DSS Wide Field - Full Res (For Print), 3522 × 3520
    tif (33.31 MB)
  • DSS Wide Field, 2000 × 1999
    jpg (2.77 MB)
  • Hubble Field 1 - Full Res (For Display), 3901 × 4012
    png (28.04 MB)
  • Hubble Field 1 - Full Res (For Print), 3901 × 4012
    tif (34.39 MB)
  • Hubble Field 1, 1945 × 2000
    jpg (1.32 MB)
  • Hubble Field 2 - Full Res (For Display), 3960 × 3855
    png (27.68 MB)
  • Hubble Field 2 - Full Res (For Print), 3960 × 3855
    tif (34.36 MB)
  • Hubble Field 2, 2000 × 1947
    jpg (1.56 MB)
At left is the Digitized Sky Survey view of the Draco dwarf galaxy. Many yellow, blue-white, and white stars are dispersed across the black background of space. They vary in shape and size, though most resemble small, circular points of light. Larger stars, some with four diffraction spikes, are scattered infrequently across the field of view. A thin, light brown oval highlights the area of interest, which contains two small white squares in its center. The area of each square is magnified at right, showing views captured by the Hubble Space Telescope. The top right square reveals a black patch of space with many small points of light and a large, four-point diffraction spike toward the left. The bottom right square shows a black patch of space filled with small points of light, some with diffraction spikes.
Color Info
Color InfoA brief description of the methods used to convert telescope data into the color image being presented.

These images are a composite of separate exposures acquired by the WFC3/UVIS and ACS instruments on the Hubble Space Telescope. Several filters were used to sample various wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Cyan= F606W, Orange= F814W

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Details

Last Updated
Mar 06, 2025
Contact
Media

Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov

Science Credit

NASA, ESA, DSS, Eduardo Vitral (STScI), Roeland van der Marel (STScI), Sangmo Tony Sohn (STScI)

Image Processing Credit

Joseph DePasquale (STScI)

Related Terms

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