Credit: NASA/JPL-Caltech/K. Gordon (University of Arizona)

Three Faces of Andromeda

NASA's Spitzer Space Telescope has captured stunning infrared views of the famous Andromeda galaxy to reveal insights that were only hinted at in visible light.

Spitzer's 24-micron mosaic (top panel) is the sharpest image ever taken of the dust in another spiral galaxy. This is possible because Andromeda is a close neighbor to the Milky Way at a mere 2.5 million light-years away.

The Spitzer multiband imaging photometer's 24-micron detector recorded 11,000 separate snapshots to create this new comprehensive picture. Asymmetrical features are seen in the prominent ring of star formation. The ring appears to be split into two pieces, forming the hole to the lower right. These features may have been caused by interactions with satellite galaxies around Andromeda as they plunge through its disk.

Spitzer also reveals delicate tracings of spiral arms within this ring that reach into the very center of the galaxy. One sees a scattering of stars within Andromeda, but only select stars that are wrapped in envelopes of dust light up at infrared wavelengths.

This is a dramatic contrast to the traditional view at visible wavelengths (lower left panel), which shows the starlight instead of the dust. The center of the galaxy in this view is dominated by a large bulge that overwhelms the inner spirals seen in dust. The dust lanes are faintly visible in places, but only where they can be seen in silhouette against background stars.

The multi-wavelength view of Andromeda (lower right panel) combines images taken at 24 microns (blue), 70 microns (green), and 160 microns (red). Using all three bands from the multiband imaging photometer allows astronomers to measure the temperature of the dust by its color. The warmest dust is brightest at 24 microns while the coolest is most evident at 160 microns. The blue/white areas have the hottest dust, as seen in the bulge and in the star-forming areas along the arms. The cooler dust floating further out in the ring and arms are in the redder regions.

The data were taken on August 25, 2004, the one-year anniversary of the launch of the space telescope. The observations have been transformed into this remarkable gift from Spitzer -- the most detailed infrared image of the spectacular galaxy to date.

About the Object	Object Name: Andromeda Galaxy (M31) Object Type: spiral galaxy Position (J2000): RA: 00h42m44.3s Dec: +41d16m09s Distance: 780,000 pc; 2.5 million light-years Constellation: Andromeda
About the Data	Image Credit: NASA/JPL-Caltech/K. Gordon (University of Arizona) Instrument: MIPS Wavelength: 24 microns (pseudocolor); also 24 microns (blue), 70 microns (green), and 160 microns (red) Exposure Date: 2004 August 25 Exposure Time: 100 sec/pixel (24 microns), 40 sec/pixel (70 microns), 9 sec/pixel (160 microns) Image Scale: 2.8 x 0.8 degrees Orientation: North is 53 deg CCW from up Release Date: October 13, 2005
Observers	Karl D. Gordon (University of Arizona) Jeremy Bailin (Swinburne University of Technology, Australia) Charles W. Engelbracht (University of Arizona) George H. Rieke (University of Arizona) Karl A. Misselt (University of Arizona) William B. Latter (SSC/Caltech) E. T. Young (University of Arizona) Matthew L. N. Ashby (Harvard-Smithsonian Center for Astrophysics) Pauline Barmby (Harvard-Smithsonian Center for Astrophysics) Brad K. Gibson (Swinburne University of Technology, Australia) Dean C. Hines (University of Colorado) Joannah Hinz (University of Arizona) Oliver Krause (University of Arizona) Deborah A. Levine (SSC/Caltech) Francine R. Marleau (SSC/Caltech) Alberto Noriega-Crespo (SSC/Caltech) Susan Stolovy (SSC/Caltech) David A. Thilker (Johns Hopkins University) M. W. Werner (JPL)

Individual Images

	MIPS 24-micron image. Screen-Resolution (450x132): JPEG High-Resolution (8193x2410): JPEG | Mac TIFF | PC TIFF Credit: NASA/JPL-Caltech/K. Gordon (University of Arizona)
	MIPS three-channel image. Screen-Resolution (450x132): JPEG High-Resolution (2071x609): JPEG | Mac TIFF | PC TIFF Credit: NASA/JPL-Caltech/K. Gordon (University of Arizona)
	Visible-light comparison image from NOAO. Screen-Resolution (450x132): JPEG High-Resolution (8193x2410): JPEG | Mac TIFF | PC TIFF Credit: NOAO/AURA/NSF

The Spitzer Space Telescope is a NASA mission managed by the Jet Propulsion Laboratory. This website is maintained by the Spitzer Science Center, located on the campus of the California Institute of Technology and part of NASA's Infrared Processing and Analysis Center.