The eXtreme Deep Field, or XDF, was assembled by combining 10 years of NASA Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra Deep Field. The XDF is a small fraction of the angular diameter of the full Moon.
The Hubble Ultra Deep Field is an image of a small area of space in the constellation Fornax, created using Hubble Space Telescope data from 2003 and 2004. By collecting faint light over many hours of observation, it revealed thousands of galaxies, both nearby and very distant, making it the deepest image of the universe ever taken at that time.
The new full-color XDF image reaches much fainter galaxies, and includes very deep exposures in red light from Hubble's new infrared camera, enabling new studies of the earliest galaxies in the universe. The XDF contains about 5,500 galaxies even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness of what the human eye can see.
Magnificent spiral galaxies similar in shape to our Milky Way and the neighboring Andromeda galaxy appear in this image, as do the large, fuzzy red galaxies where the formation of new stars has ceased. These red galaxies are the remnants of dramatic collisions between galaxies and are in their declining years. Peppered across the field are tiny, faint, more distant galaxies that were like the seedlings from which today's striking galaxies grew. The history of galaxies – from soon after the first galaxies were born to the great galaxies of today, like our Milky Way – is laid out in this one remarkable image.
Hubble pointed at a tiny patch of southern sky in repeat visits (made over the past decade) for a total of 50 days, with a total exposure time of 2 million seconds. More than 2,000 images of the same field were taken with Hubble's two premier cameras – the Advanced Camera for Surveys and the Wide Field Camera 3, which extends Hubble's vision into near-infrared light – and combined to make the XDF.
"The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen. XDF allows us to explore further back in time than ever before," said Garth Illingworth of the University of California at Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 (HUDF09) program.
The universe is 13.7 billion years old, and the XDF reveals galaxies that span back 13.2 billion years in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, often violently as they collided and merged together. The early universe was a time of dramatic birth for galaxies containing brilliant blue stars extraordinarily brighter than our Sun. The light from those past events is just arriving at Earth now, and so the XDF is a "time tunnel into the distant past." The youngest galaxy found in the XDF existed just 450 million years after the universe's birth in the big bang.
Credits
NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team| About The Object | |
|---|---|
| Object Name | Hubble eXtreme Deep Field, XDF |
| Object Description | Optical and Infrared Survey |
| R.A. Position | 03h 32m 38.5s |
| Dec. Position | -27° 47' 0.0" |
| Constellation | Fornax |
| Distance | The image is 2.3 arcminutes by 2 arcminutes in size. |
| About The Data | |
| Data Description | The image was created from Hubble data from the following proposals: , , , and : A. Riess (STScI/JHU); : M. Giavalsco (University of Massachusetts); : K. Ratnatunga (Carnegie Mellon University); : W. Sparks (STScI); and : S. Malhotra (Arizona State University); and : S. Beckwith (STScI); : C. Kretchmer (JHU); : R. O'Connell (University of Virginia); : G. Illingworth (University of California, Santa Cruz); - : S. Faber (University of California, Santa Cruz); : P. van Dokkum (Yale University). The XDF/HUDF09 team members include: G. Illingworth (University of California, Santa Cruz), R. Bouwens (Leiden University), M. Carollo (Swiss Federal Institute of Technology, Zurich (ETH)), M. Franx (Leiden University), V. Gonzalez (University of California, Santa Cruz), I. Labbe (Leiden University), D. Magee and P. Oesch (University of California, Santa Cruz), M. Stiavelli (STScI), M. Trenti (University of Cambridge), and P. van Dokkum (Yale University). |
| Instrument | HST>ACS/WFC and HST>WFC3/IR |
| Exposure Dates | July 2002 to March 2012, Exposure Time: 22.5 days (2 million seconds) |
| Filters | ACS/WFC: F435W (B), F606W (V), F775W (I), F814W (I), and F850LP (z) WFC3/IR: F105W (Y), F125W (J), and F160W (H) |
| About The Image | |
| Color Info | This image is a composite of separate exposures acquired by the ACS and WFC3/IR instruments. Several filters were used to sample various wavelengths. The color results from assigning different hues (colors) to each monochromatic (grayscale) image from the eight different filters used by the two instruments grouped as follows: Blue: ACS/WFC F435W (B) + F606W (V) Green: ACS/WFC F775W (I) + F814W (I) + F850LP (z) Red: WFC3/IR F105W (Y) + F125W (J) + F160W (H) |
| Compass Image |  |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
