A team of astronomers using the Advanced Camera for Surveys on NASA’s Hubble Space Telescope has obtained the sharpest image ever taken of our galactic neighbor, otherwise known as Messier 31 (M31).
Andromeda Galaxy. Image credit: NASA / ESA / University of Washington / PHAT team / J. Dalcanton / B. F. Williams / L. C. Johnson / R. Gendler.
Though the Andromeda Galaxy is 2.5 million light-years away, Hubble is powerful enough to resolve individual stars in a 61,000-light-year-long section of the galaxy’s pancake-shaped disk. It’s like photographing a beach and resolving individual grains of sand.
This ambitious photographic cartography of the galaxy represents a new benchmark for precision studies of large spiral galaxies which dominate the Universe’s population of over 100 billion galaxies.
Never before have astronomers been able to see individual stars over a major portion of an external spiral galaxy.
This new panoramic image of the Andromeda Galaxy is the product of the Panchromatic Hubble Andromeda Treasury (PHAT) programme.
It has a staggering 1.5 billion pixels – meaning you would need more than 600 HD television screens to display the whole image.
The PHAT mosaic is shown in context with a ground-based image of the Andromeda Galaxy (Messier 31 or M31). The background image, taken by Robert Gendler, was made by compositing M31 data from a 12.5-inch Ritchey-Chretien telescope with M31 data from the Digitized Sky Survey. Image credit: NASA / ESA / Z. Levay / STScI / AURA / University of Washington / PHAT team / J. Dalcanton / B. F. Williams / L. C. Johnson / R. Gendler.
It traces the galaxy from its central galactic bulge on the left, where stars are densely packed together, across lanes of stars and dust to the sparser outskirts of its outer disc on the right.
The large groups of blue stars in the galaxy indicate the locations of star clusters and star-forming regions in the spiral arms, whilst the dark silhouettes of obscured regions trace out complex dust structures.
Underlying the entire galaxy is a smooth distribution of cooler red stars that trace galaxy’s evolution over billions of years.
To capture the large portion of the Andromeda Galaxy seen here – over 40,000 light-years across – the astronomers took 411 images which have been assembled into a mosaic image.
This view shows the galaxy in its natural visible-light color, as photographed with Hubble’s Advanced Camera for Surveys in red and blue filters July 2010 through October 2013.
The image was presented January 6 at the 225th Meeting of the American Astronomical Society in Seattle, Washington.
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