Hubble Ultra Deep Field

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The HUDF shows galaxies of different ages, sizes and shapes. The smallest, reddest galaxies, roughly 100 in number, are among the most distant galaxies known to date. According to the theory of the Big Bang about 13.8 billion years ago, these galaxies can be seen at a stage when the universe was no older than 800 million years.

The Hubble Ultra Deep Field ( HUDF ) is an image of a small region of the sky captured by the Hubble Space Telescope from September 3, 2003 to January 16, 2004. It was the deepest image until the Hubble Extreme Deep Field was released in September 2012 of the universe in the range of visible light . A region of the sky was selected that contains hardly any disturbing bright stars in the foreground. It was decided on a target area in the chemical furnace constellation southwest of Orion . It is at right ascension 3h 32 m 39.0s and declination−27 ° 47 '29.1 ″. The diameter of the selected section of the sky corresponds to about a tenth of the diameter of the moon when viewed from the earth. This corresponds to an area of ​​one square millimeter at a distance of one meter and represents approximately one forty millionth of the entire sky. The HUDF contains around 10,000 galaxies and large cosmic objects. It consists of two separate recordings by Hubble's “Advanced Camera for Surveys” (ACS) and the “Near Infrared Camera and Multi-Object Spectrometer” (NICMOS). The picture was created from 800 individual exposures that were carried out during 400 orbits of Hubble. The total exposure time was 11.3 days for ACS and 4.5 days for NICMOS. It would take the Hubble Space Telescope a million years to observe the entire sky at this resolution.

The Hubble Ultra Deep Field is in the tradition of the Hubble Deep Field and Hubble Deep Field South , which were recorded with the old WFPC2 camera , are less deep and cover a smaller field. After installing the WFC3 / IR camera, the same area of ​​the sky was recorded at the end of August 2009 in the near infrared at the wavelengths 1.05, 1.25 and 1.6 micrometers as HUDF09 over four days with a total exposure time of 48 hours.

Scientific importance

The same picture as above in a larger resolution
Direction of recording relative to the earth

The HUDF shows the faintest galaxies that have been observed up to then, and thus also the furthest away (one speaks of the “depth” of the image). Because of the finite speed of light , the time it takes to travel from the most distant galaxies to us is over 13 billion years. According to the cosmological standard model, one looks back to the early days of the universe 800 million years after the Big Bang . The image shows some of the first galaxies that arose after the so-called dark age . Investigations into the formation and evolution of galaxies were the main motivation for the project.

In fact, the HUDF pointed out that the proportion of irregular galaxies increases with redshift , i.e. with distance, whereas the average galaxy size decreases. The star formation rate was significantly higher than today at a high redshift.

When interpreting the observations, it should be noted that light that we observe from distant galaxies in the visible range was actually emitted in the ultraviolet because of the cosmological redshift . Visual observations of the morphology of distant galaxies must therefore be compared with the corresponding observations of local galaxies in the ultraviolet. Alternatively, one can observe distant galaxies in the infrared light , which was emitted as visible light by the galaxies. The Spitzer Space Telescope (launched on August 25, 2003) and the Herschel Space Telescope (launched on May 14, 2009), as well as the future successor to the Hubble Space Telescope, the James Webb Space Telescope (planned to start in 2021), played a role here . The latter is designed for observations in the near infrared.

literature

Web links

Commons : Hubble Ultra Deep Field  - Album with pictures, videos and audio files

Individual evidence

  1. ↑ Ross Pomeroy: The Astounding Truth About the Hubble Space Telescope's Most Famous Image RealClearScience, accessed April 17, 2020.
  2. ↑ Hubble's Deepest View Ever of the Universe Unveils Earliest Galaxies , NASA, March 9, 2004
  3. ↑ Hubble's Deepest View of Universe Unveils Never-Before-Seen Galaxies , NASA, August 12, 2009