2,65,000 galaxies in an extensive legacy field mosaic

Astronomers developed a mosaic of the distant Universe that documents 16 years of observations from the NASA/ESA Hubble Space Telescope. The image, called the Hubble Legacy Field, contains roughly 265,000 galaxies that stretch back to just 500 million years after the Big Bang.

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NASA’s Hubble Space Telescope has recently captured an image of a legacy field, showing 2,65,000 galaxies, each at different stages in their life cycles, but also the history of the universe. Even if it seems unassuming on the first glance, the image is a big deal for astronomers.

The image is a mosaic of different images captured by the Hubble Space Telescope as part of its deep-field surveys, arranged into a giant overview called the Hubble Legacy Field. The wavelength range of this image stretches from ultraviolet to near-infrared light, capturing all the features of galaxy assembly over time. The faintest and farthest galaxies in the image are just one ten-billionth the brightness of what the human eye can observe.

This image, called the Hubble eXtreme Deep Field (XDF), combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made, combining data from previous images including the Hubble Ultra Deep Field (taken in 2002 and 2003) and Hubble Ultra Deep Field Infrared (2009). The image covers an area less than a tenth of the width of the full Moon, making it just a 30 millionth of the whole sky. Yet even in this tiny fraction of the sky, the long exposure reveals about 5500 galaxies, some of them so distant that we see them when the Universe was less than 5% of its current age. The Hubble eXtreme Deep Field image contains several of the most distant objects ever identified.
This image, called the Hubble eXtreme Deep Field (XDF), combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made, combining data from previous images including the Hubble Ultra Deep Field (taken in 2002 and 2003) and Hubble Ultra Deep Field Infrared (2009). The image covers an area less than a tenth of the width of the full Moon, making it just a 30 millionth of the whole sky. Yet even in this tiny fraction of the sky, the long exposure reveals about 5500 galaxies, some of them so distant that we see them when the Universe was less than 5% of its current age. The Hubble eXtreme Deep Field image contains several of the most distant objects ever identified.

Garth Illingworth of the University of California, Santa Cruz, leader of the team that assembled the image said, “Now that we have gone wider than in previous surveys, we are harvesting many more distant galaxies in the largest such dataset ever produced. No image will surpass this one until future space telescopes like James Webb are launched.”

The Legacy Field is no ordinary map, and naturally, took an extraordinary effort on the part of Hubble and the scientists programming it. The telescope spent 250 days staring into this one patch of sky. Moreover, there were 31 programs of astronomers that made this image a reality. This spectacular new window into the universe was shared with the public on 2 May 2019.

This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. The snapshot includes galaxies of various ages, sizes, shapes, and colours. The smallest, reddest galaxies, about 100, may be among the most distant known, existing when the universe was just 800 million years old. The nearest galaxies - the larger, brighter, well-defined spirals and ellipticals - thrived about 1 billion years ago, when the cosmos was 13 billion years old. The image required 800 exposures taken over the course of 400 Hubble orbits around Earth. The total amount of exposure time was 11.3 days, taken between Sept. 24, 2003 and Jan. 16, 2004.
This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. The snapshot includes galaxies of various ages, sizes, shapes, and colours. The smallest, reddest galaxies, about 100, may be among the most distant known, existing when the universe was just 800 million years old. The nearest galaxies – the larger, brighter, well-defined spirals and ellipticals – thrived about 1 billion years ago, when the cosmos was 13 billion years old. The image required 800 exposures taken over the course of 400 Hubble orbits around Earth. The total amount of exposure time was 11.3 days, taken between Sept. 24, 2003 and Jan. 16, 2004.

Team member Rychard Bouwens of Leiden University in the Netherlands said, “One exciting aspect of these new images are a large number of sensitive color channels now available to view distant galaxies, especially in the ultraviolet part of the spectrum. With images at so many frequencies, we can dissect the light from galaxies into the contributions from old and young stars, as well as active galactic nuclei.”

Several hundred never before seen galaxies are visible in this 'deepest-ever' view of the universe, called the Hubble Deep Field (HDF), made with the Hubble Space Telescope. Besides the classical spiral and elliptical shaped galaxies, there is a bewildering variety of other galaxy shapes and colours that are important clues to understanding the evolution of the universe. Some of the galaxies may have formed less that one billion years after the Big Bang.
Several hundred never before seen galaxies are visible in this ‘deepest-ever’ view of the universe, called the Hubble Deep Field (HDF), made with the Hubble Space Telescope. Besides the classical spiral and elliptical shaped galaxies, there is a bewildering variety of other galaxy shapes and colours that are important clues to understanding the evolution of the universe. Some of the galaxies may have formed less that one billion years after the Big Bang.

The Legacy Field image and other deep-field images show the expansion of the universe, giving astronomers clues to the state of the early universe and the way that it evolved over millions of years. New telescopes like the upcoming James Webb Telescope will allow astronomers to look even deeper into space, learning more about the development of galaxies through time.

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