Largest Hubble Space Telescope image ever assembled offers awesome view of a portion of the Andromeda galaxy

Captures individual stars 2 million light-years away
January 6, 2015

Hubble’s high-definition panoramic view of a portion of the Andromeda Galaxy (click twice to see individual stars). The largest NASA Hubble Space Telescope image ever assembled, this image is also the sharpest composite image ever taken of the Andromeda Galaxy (credit: NASA, ESA, J. Dalcanton, B.F. Williams, and L.C. Johnson (U. of Washington), the Panchromatic Hubble Andromeda Treasury (PHAT) team, and R. Gendler)

NASA announced Monday the largest NASA Hubble Space Telescope image ever assembled — a sweeping bird’s-eye view of a portion of the Andromeda galaxy (M31) and the sharpest large composite image ever taken of our nearest galaxy. The galaxy is over 2 million light-years away, but the Hubble Space Telescope is powerful enough to resolve individual stars in a 61,000-light-year-long stretch of the galaxy’s pancake-shaped disk. This is the first image of stars over such a large contiguous area.

NASA says these images represent a new benchmark for precision studies of large spiral galaxies.

Hubble traces densely packed stars extending from the innermost hub of the galaxy seen at the left. Moving out from this central galactic bulge, the panorama sweeps from the galaxy’s central bulge across lanes of stars and dust to the sparser outer disk. Large groups of young blue stars indicate the locations of star clusters and star-forming regions. The stars bunch up in the blue ring-like feature toward the right side of the image. The dark silhouettes trace out complex dust structures. Underlying the entire galaxy is a smooth distribution of cooler red stars that trace Andromeda’s evolution over billions of years.

Because the galaxy is only 2.5 million light-years from Earth, it is a much bigger target in the sky than the myriad galaxies Hubble routinely photographs that are billions of light-years away. The huge view requires assembly into a mosaic image using 7,398 exposures, taken over 411 individual pointings.

The panorama is being presented at the 225th Meeting of the Astronomical Society in Seattle, Washington.