Mosaic image shows details of over 100 million stars
SEATTLE — The Andromeda galaxy is ready for its close-up.
The closest spiral galaxy to the Milky Way appears in unprecedented detail in a new mosaic of images from the Hubble Space Telescope presented January 5 at the American Astronomical Society meeting. The final composite is a 61,000-light-year-long panorama of our galactic neighbor encompassing the light of nearly 117 million stars.
Even though Andromeda is over 2 million light-years away, the picture contains enough detail to reveal individual stars and star clusters. The center of the galaxy, filled with old red stars, sits to one side of the image. Spiral arms, home to Andromeda’s stellar nurseries, encircle the mostly dead core with young, blue stars and tendrils of dark dust.
The image is a result of the Panchromatic Hubble Andromeda Treasury, a multi-year project to study the formation and evolution of stars by mapping part of Andromeda’s disk with the Hubble telescope. The composite shot comprises 7,398 individual exposures acquired from July 2010 to October 2013.
Editor’s note: This story was updated January 12, 2015, to correct the distance of the Andromeda galaxy to 2 million (not billion) light-years away.
J. Dalcanton et al. A 20pc resolution dust map of M31 from the Panchromatic Hubble Andromeda Treasury (PHAT). January 5, 2015, American Astronomical Society Meeting, Seattle.
B.F. Williams et al. The Panchromatic Hubble Andromeda Treasury Survey: UV-IR photometry of 117 million stars. January 7, 2015, American Astronomical Society meeting, Seattle.
C. Crockett. Nearly starless galaxies found in nearby cluster.Science News. Vol. 186, December 13, 2014, p. 9.
C. Crockett. Milky Way connected to a vast network of galaxies.Science News. Vol. 186, October 4, 2014, p. 15.
A. Witze. Milky Way will be hit head-on. Science News. Vol. 182, July 14, 2012, p. 10.