ESA’s Euclid spacecraft has taken a stunning image of the irregular galaxy NGC 6822, which is located in the constellation of Sagittarius.
This Euclid image shows NGC 6822, an irregular dwarf galaxy some 1.5 million light-years away in the constellation of Sagittarius. Image credit: ESA / NASA / Euclid / Euclid Consortium / J.-C. Cuillandre, CEA Paris-Saclay / G. Anselmi / CC BY-SA 3.0 IGO.
NGC 6822 lies approximately 1.5 million light-years away in the constellation of Sagittarius.
Also known as Barnard’s Galaxy, IC 4895, or Caldwell 57, this galaxy is similar in structure and composition to the Small Magellanic Cloud.
NGC 6822 has a diameter of 7,000 light-years and belongs to the Local Group of galaxies.
It has a low metallicity, meaning that it contains low proportions of elements that are not hydrogen and helium.
NGC 6822 was discovered by the American astronomer Edward Emerson Barnard in 1884.
In 1925, the American astronomer Edwin Hubble — namesake of the NASA/ESA Hubble Space telescope — was the first to identify NGC 6822 as a ‘remote stellar system’ well beyond the Milky Way.
“NGC 6822 has been observed many times since, most recently by the NASA/ESA/CSA James Webb Space Telescope,” said members of the Euclid Consortium.
“But Euclid is the first to capture the entire galaxy and its surroundings in high resolution in about one hour, which would not be possible with telescopes on the ground (the atmosphere prevents this sharpness) or with Webb (which makes very detailed images of small parts of the sky).”
“One interesting aspect of this galaxy is that its stars contain low amounts of elements that are not hydrogen and helium.”
“These heavier, metal elements are produced by stars over their lifetimes and are therefore not very common in the early Universe.”
“By studying low-metallicity galaxies like NGC 6822 in our own Galactic neighborhood, we can learn how galaxies evolved in the early Universe,” said Dr. Leslie Hunt, an astronomer at the National Institute for Astrophysics and a member of the Euclid Consortium.
In addition to studying the star-formation history of this galaxy, which can now be done thanks to the colour information from Euclid’s near-infrared instrument and its wide field of view, scientists have already spotted many globular star clusters in this image that reveal clues as to how the galaxy was assembled.
“Globular clusters are collections of hundreds of thousands of stars held together by gravity,” the astronomers said.
“They are some of the oldest objects in the Universe, and most of their stars were all formed out of the same cloud.”
“That’s why they hold the ‘fossil records’ of the first star-formation episodes of their host galaxies.”
