The Hubble Deep Field Survey
The Hubble Space Telescope spent 10 days in December 1995 observing a single tiny patch of sky near the Big Dipper. These observations resulted in the deepest image of the sky, called the Hubble Deep Field (HDF), revealing galaxies fainter than had ever been seen before. The striking full-color image of the distant universe was unveiled at the American Astronomical Society Meeting in January 1996.
"The variety of galaxies we see is amazing. In time these Hubble data could turn out to be the double helix of galaxy formation. We are clearly seeing some of the galaxies as they were more than ten billion years ago, in the process of formation. As the images have come up on our screens, we have not been able to keep from wondering if we might somehow be seeing our own origins in all of this." -- Robert Williams, Director, Space Telescope Science Institute (STScI), Baltimore, Maryland
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Hubble's Deepest-Ever View
of the Universe Credit: Robert Williams and the Hubble Deep Field Team (STScI) and NASA Several hundred never before seen galaxies are visible in this "deepest-ever" view of the universe, called the Hubble Deep Field (HDF), made with NASA's Hubble Space Telescope. Besides the classical spiral and elliptical shaped galaxies, there is a bewildering variety of other galaxy shapes and colors 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 image was assembled from many separate exposures (342 frames total were taken, 276 have been fully processed to date and used for this picture) with the Wide Field and Planetary Camera 2 (WFPC2), for ten consecutive days between December 18 to 28, 1995. This picture is from one of three wide-field CCD (Charged Coupled Device) detectors on the WFPC2. This "true-color" view was assembled from separate images were taken in blue, red, and infrared light. By combining these separate images into a single color picture, astronomers will be able to infer -- at least statistically -- the distance, age, and composition of galaxies in the field. Bluer objects contain young stars and/or are relatively close, while redder objects contain older stellar populations and/or farther away. |
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Sample Galaxies From the Hubble Deep Field Credit: Robert Williams and the Hubble Deep Field Team (STScI) and NASA These three images represent select portions of the sky as seen in the Hubble Deep Field observation -- the "deepest-ever" view of the universe, made with NASA's Hubble Space Telescope. The images, extracted from the Hubble Deep Field (HDF), were assembled from many separate exposures (342 frames total were taken, 276 have been fully processed to date and used for this picture) with the Wide Field and Planetary Camera 2 (WFPC2), for ten consecutive days between December 18 to 28, 1995. Besides the classical spiral- and elliptical-shaped galaxies, there is a bewildering variety of other galaxy shapes and colors. The never before seen dimmest galaxies are nearly 30th magnitude. |
The Deep Field in Infrared
Credit: Rodger I. Thompson (University of Arizona), and NASA
[Left]
A NASA Hubble Space Telescope view of the faintest galaxies ever seen in the universe, taken in infrared light with the Near Infrared Camera and
Multi-Object Spectrometer (NICMOS).
The picture contains over 300 galaxies having spiral, elliptical and irregular shapes. Though most of these galaxies were first seen in 1995 when Hubble was used to take a visible-light deep exposure of the same field, NICMOS uncovers many new objects. Most of these objects are too small and faint to be apparent in the full field NICMOS view.
Some of the reddest and faintest of the newly detected objects may be over 12 billion light-years away, as derived from a standard model of the universe. However, a powerful new generation of telescopes will be needed to confirm the suspected distances of these objects.
The field of view is 2 million light-years across, at its maximum. Yet, on a cosmic scale, it represents only a thin pencil beam look across the universe. The area of sky is merely 1/100th the apparent diameter on the full moon.
[Right]
Two close-up NICMOS views of candidate objects which may be over 12 billion light-years away. Each candidate is centered in the frame. The
reddish color may mean all of the starlight has been stretched to infrared wavelengths by the universe's expansion. Alternative
explanations are that the objects are closer to us, but the light has been reddened by dust scattering. A new generation of telescopes will be
needed to make follow-up observations capable of establishing true distance.
The image was taken in January 1998 and required an exposure time of 36 hours to detect objects down to 30th magnitude. The color corresponds to blue (0.45 microns), green (1.1 microns) and red (1.6 microns).
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Hubble Deep Field South Unveils Myriad Galaxies Credit: R. Williams (STScI), the HDF-S Team, and NASA A NASA Hubble Space Telescope view down a 12 billion light-year long corridor of space loaded with a dazzling assortment of thousands of never-before seen galaxies. This picture is the culmination of a 10-day-long observation called the Hubble Deep Field South (HDF-S) which was carried out in October 1998 by a team of astronomers at the Space Telescope Science Institute (STScI) and the Goddard Space Flight Center.
Hubble’s sharp vision allows astronomers to sort galaxy shapes. The image is dominated by beautiful pinwheel-shaped disk galaxies, which are like our Milky Way. The picture also contains a variety of peculiar-shaped galaxies that are in collision with companion galaxies. Elliptical galaxies appear as reddish blobs. A sprinkling of foreground stars (belonging to our Milky Way) appear as bright points with "diffraction spikes" an artifact of all telescope optics. The colors in the pictures are a natural representation of the galaxies’ stellar populations. Blue corresponds to young hot stars. Red may indicate older stars, starlight scattered by dust, or very distant starlight that has been stretched to redder wavelengths by the universe’s expansion. Follow-up observations with large ground-based telescopes in the southern hemisphere will establish the distances to the galaxies. This will help astronomers understand the history of the universe because the galaxies represent the universe at different epochs, depending on their distances. |
Hubble Deep Field South -- Multiple Windows on the Universe
Credit: R. Williams (STScI), the HDF-S Team, and NASA
Peering at a small patch of sky near the south celestial pole, NASA's Hubble Space Telescope used its full array of instruments to look nearly all the way across the universe. Called the Hubble Deep Field South (HDF-S), this new far-look complements the original Hubble "deep field" taken in late 1995, when Hubble was aimed at a small patch of space in the opposite direction on the sky, near the north celestial pole.
[lower left] - The carefully selected HDF-S target field in the constellation Tucana, as imaged by the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. The field of view is 15 arc minutes, approximately half the angular diameter of the full moon. The respective fields of Hubble’s three instruments are outlined.
[upper left] - The deepest visible/ultraviolet light image of the universe ever taken, revealing galaxies down to 30th magnitude. Glaring fiercely across 12 billion light-years of space is the brilliant beacon of a distant quasar (z=2.2). Most of the galaxies in this view lie between us and the quasar. The image was taken with the camera on the Space Telescope Imaging Spectrograph (STIS). The STIS recorded how numerous invisible intervening clouds of hydrogen gas affected the quasar’s light. Some of the galaxies in the image may be linked to these clouds.
[upper right] - Several thousand never-before-seen spiral, elliptical and colliding galaxies snap into view in this Hubble Wide Field Planetary Camera 2 (WFPC2) image. The image has a striking similarity to the WFPC2’s picture of the northern deep field. The full color picture can be used to estimate galaxy distance and ages.
[lower right] - Hubble’s Near Infrared and Multi-Object Spectrometer (NICMOS) captures the "invisible light" coming from stars hidden in dusty galaxies, and galaxies that are so far away their light has been stretched beyond the red end of the visible spectrum.
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Combined Deep View of Infrared and Visible Light Galaxies Credit: R. Williams (STScI) and the HDF-South team, and NASA This narrow, deep view of the universe reveals a plethora of galaxies (reaching fainter than 28th magnitude), as seen in visible and infrared light by NASA’s Hubble Space Telescope. The reddish galaxies are glowing in infrared light, and the bluish galaxies are glowing in visible light. Several distinctive types of galaxies can be seen in these views: blue dwarf galaxies, disk galaxies, and very red elliptical galaxies. A bright, nearby face-on spiral galaxy appears at upper right. Some of the brightest objects in the field are foreground stars in the halo of our own Milky Way galaxy. By combining views in infrared light and visible light astronomers have a better idea of the shapes of galaxies in the remote universe, and of the fraction which are old or dust-obscured at early epochs. Galaxies could appear bright in the infrared (and thus red in this picture) for several reasons. They might be dusty, or contain old stars, or are at a very great distance. Several of the red galaxies in this field have the colors and the smooth, symmetric shapes expected for old elliptical galaxies. The existence of such objects in the early universe and their numbers can set important limits on the era when the earliest galaxies assembled and formed most of their stars. In general, the image shows that the shapes and sizes of most faint galaxies are similar in infrared and visible light, suggesting that younger and older stars within distant galaxies are well mixed and that dust is not completely distorting impressions of distant objects. The image was taken in October 1998 as part of the Hubble Deep Field South imaging campaign. It is in a small patch of sky in the constellation Tucana. The false-color image is a composite of separate images taken with the NICMOS and STIS cameras on board the Hubble Space Telescope. The red and green colors correspond to infrared wavelengths of 1.6 and 1.1 microns, respectively. The blue color corresponds to the STIS view that covers the full range of visible wavelengths. |
The Most Distant Supernova Ever Seen
Credits: NASA, Adam Riess (Space Telescope Science Institute, Baltimore, MD)
Using NASA's Hubble Space Telescope, astronomers pinpointed a blaze of light from the farthest supernova ever seen, a dying star that exploded 10 billion years ago.
The detection and analysis of this supernova, called 1997ff, is greatly bolstering the case for the existence of a mysterious form of dark energy pervading the cosmos, making galaxies hurl ever faster away from each other. The supernova also offers the first glimpse of the universe slowing down soon after the Big Bang, before it began speeding up.
This panel of images, taken with the Wide Field and Planetary Camera 2, shows the supernova's cosmic neighborhood; its home galaxy; and the dying star itself.
Astronomers found this supernova in 1997 during a second look at the northern Hubble Deep Field [top panel], a tiny region of sky first explored by the Hubble telescope in 1995. The image shows the myriad of galaxies Hubble spied when it peered across more than 10 billion years of time and space. The white box marks the area where the supernova dwells.
The photo at bottom left is a close-up view of that region. The white arrow points to the exploding star's home galaxy, a faint elliptical. Its redness is due to the billions of old stars residing there.
The picture at bottom right shows the supernova itself, distinguished by the white dot in the center. Although this stellar explosion is among the brightest beacons in the universe, it could not be seen directly in the Hubble images. The stellar blast is so distant from Earth that its light is buried in the glow of its host galaxy.
To find the supernova, astronomers compared two pictures of the "deep field" taken two years apart. One image was of the original Hubble Deep Field; the other, the follow-up deep-field picture taken in 1997. Using special computer software, astronomers then measured the light from the galaxies in both images. Noting any changes in light output between the two pictures, the computer identified a blob of light in the 1997 picture that wasn't in the original deep-field study. That blob turned out to be the supernova. The red background texture is an artifact of the process of isolating the supernova.
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Very Distant Galaxy Clusters
Credit: ESO During the past years, it has become possible to detect and subsequently study progressively more distant clusters of galaxies. For this research program, UT1 Science Verification data were used, in combination with data obtained with the SOFI instrument at the ESO New Technology Telescope (NTT) at La Silla, to confirm the existence of two very distant galaxy clusters at redshift z ~ 1, that had originally been detected in the ESO Imaging Survey. This redshift corresponds to an epoch when the age of the Universe was only two-thirds of the present. The image is a color composite that shows the now confirmed cluster EIS0046-2930. The image has been produced by combining the V (green-yellow), R (red) and I (Near-IR) exposures with the Test Camera obtained during the VLT-UT1 Science Verification. The yellow-orange galaxies are the cluster members and the bluer objects are galaxies belonging to the general field population. The cluster center is at the location of the largest (yellow-orange) cluster galaxy to the left of the center of the image. The field measures 90 x 90 arcsec. This was achieved by the detection of a spatial excess density of galaxies, with measured color equal to that of elliptical galaxies at this redshift, as established by counts in the respective sky areas. The field of one these clusters is shown here. These new data show that the VLT will most certainly play a major role in the studies of the cluster galaxy population in such distant systems. This will contribute to shed important new light on the evolution of galaxies. Furthermore, the VLT clearly has the potential to identify and confirm the reality of many more such clusters and thereby to increase considerably the number of known objects. This will be important in order to determine more accurate values of the basic cosmological constants, and thus for our understanding of the evolution of the Universe as a whole. |
The Hubble Ultra Deep Field
Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team
Galaxies, galaxies everywhere - as far as NASA's Hubble Space Telescope can see. This view of nearly 10,000 galaxies is the deepest visible-light image of the cosmos. Called the Hubble Ultra Deep Field, this galaxy-studded view represents a "deep" core sample of the universe, cutting across billions of light-years.
The snapshot includes galaxies of various ages, sizes, shapes, and colors. 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.
In vibrant contrast to the rich harvest of classic spiral and elliptical galaxies, there is a zoo of oddball galaxies littering the field. Some look like toothpicks; others like links on a bracelet. A few appear to be interacting. These oddball galaxies chronicle a period when the universe was younger and more chaotic. Order and structure were just beginning to emerge.
The Ultra Deep Field observations, taken by the Advanced Camera for Surveys, represent a narrow, deep view of the cosmos. Peering into the Ultra Deep Field is like looking through an eight-foot-long soda straw.
In ground-based photographs, the patch of sky in which the galaxies reside (just one-tenth the diameter of the full Moon) is largely empty. Located in the constellation Fornax, the region is so empty that only a handful of stars within the Milky Way galaxy can be seen in the image.
In this image, blue and green correspond to colors that can be seen by the human eye, such as hot, young, blue stars and the glow of Sun-like stars in the disks of galaxies. Red represents near-infrared light, which is invisible to the human eye, such as the red glow of dust-enshrouded galaxies.
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.
Galactic Drama in Ultra Deep Field Details
Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team
A galactic brawl. A close encounter with a spiral galaxy. Blue wisps of galaxies. These close-up snapshots of galaxies in the Hubble Ultra Deep Field reveal the drama of galactic life.
Almost every panel shows oddball-shaped galaxies engaged in boxing matches with galactic neighbors. In the panel at top, left, three galaxies just below center are enmeshed in battle, their shapes distorted by the brutal encounter. The panel at top, center, reveals an edge-on spiral galaxy fending off a weirdly shaped blue galaxy. The panel at bottom, right, is littered with close encounters between galaxies that have been shredded by the interactions. These oddball galaxies chronicle a period when the universe was younger and more chaotic. Order and structure were just beginning to emerge.
Not all the galaxies are engaged in galactic mayhem. In the panel at top, right, is a majestic spiral galaxy, one of the nearest galaxies in the Ultra Deep Field. This galaxy existed about 1 billion years ago, when the cosmos was 13 billion years old. The smallest, reddest galaxies [the red dots in the panels at top, left and bottom, left] may be among the most distant known, existing when the cosmos was 800 million years old.
The galaxies in these panels were plucked from a harvest of nearly 10,000 galaxies in the Ultra Deep Field, the deepest visible-light image of the cosmos.
The Ultra Deep Field observations, taken by the Advanced Camera for Surveys, represent a narrow, "deep" view of the cosmos. Peering into the Ultra Deep Field is like looking through an eight-foot-long soda straw.
In ground-based images, the patch of sky in which the galaxies reside (just one-tenth the diameter of the full Moon) is largely empty. Located in the constellation Fornax, the region is so empty, in fact, that only a handful of stars within the Milky Way galaxy can be seen in the image.
In this image, blue and green correspond to colors that can be seen by the human eye, such as hot, young, blue stars and the glow of Sun-like stars in the disks of galaxies. Red represents near-infrared light, which is invisible to the human eye, such as the red glow of dust-enshrouded galaxies.
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.
Representing a narrow "keyhole" view all the way to the visible horizon of
the universe, the HDF image covers a speck of sky 1/30th the diameter of the full Moon
near Ursa Major (the Big Dipper). This is so narrow,
just a few foreground stars in our Milky Way galaxy are visible and are vastly outnumbered by the menagerie of far more distant galaxies, some nearly
as faint as 30th magnitude, or nearly four billion times fainter than the limits of human vision. (The relatively bright object with diffraction
spikes just left of center may be a 20th magnitude star.) Though the field is a very small sample of sky area it is considered representative of the
typical distribution of galaxies in space because the universe, statistically, looks the same in all directions.
This new "far-look" complements the original Hubble "deep field" taken in late 1995, when Hubble was aimed at a small patch of space near the Big Dipper. The new region is in the constellation Tucana, near the south celestial pole.