Radio astronomy

Radio astronomy is a subfield of astronomy, are in astronomical objects by means of radio waves that are emitted by them examined.

Cosmic Radio Astronomy

Due to the large distance of astronomical objects, the radio sources, the radio waves are very weak. Therefore, we try to bundle in radio astronomy, the radio waves with large antennas ( types such as Yagi, frame, helical and parabolic antennas ). The radio waves are amplified by sensitive amplifiers and then stored electronically and analyzed.

A certain measured value indicates the intensity with which the radio waves arrive from the direction to which the radio telescope is pointed. A " view " through a radio telescope thus gives no radio image, but only a single radio pixel.

The wavelength of the radio waves is very much larger than the wavelength of visible light, and therefore the angular resolution of a single radio telescope is much smaller than that of an optical telescope. This has the consequence that a system composed of many measurements radio telescope image is less sharp than an image of the same object taken with visible light. However, there are methods to obtain high-resolution radio images of extended astronomical objects. For example, several radio telescopes can be connected together to form an interferometer that they act as a single radio telescope whose antenna diameter equal to the distance of the individual assets of each other. Since the resolution depends on the distance of the antennas, you get significantly sharper images than with telescopes in the optical wavelength range.

Since radio waves are less absorbed by intergalactic dust and mist clouds, and as the majority of galactic celestial bodies represent only weak radio sources, you can explore via radio waves areas such as the center of the Milky Way or dwarf galaxies behind the galactic disk, the infrared - optical or observation remain closed.

On the radio wave range are some of the main spectral lines of astronomy, including the HI- line (21- cm line, 1420.4058 MHz), which is emitted by neutral hydrogen atoms.

With the radio astronomy include the following radio sources are examined:

  • The sun and other bodies in the solar system
  • Supernova remnants and pulsars
  • Interstellar gases and gaseous nebulae
  • The galactic center of the Milky Way
  • Radio galaxies
  • Quasars

The technique of radio astronomy is also applied to the search for extraterrestrial intelligence ( SETI ).

Karl Guthe Jansky observed in 1931 the first radio source outside our solar system, the galactic center of our Milky Way. His honor the unit used in radio astronomy introduced.

Subareas and research objects of radio astronomy

Objects in the solar system

  • The solar radio astronomy deals with the transmitted radio waves from the sun. These give, for example, Information on the solar activity and flares on the sun.
  • The planets, in particular the gas giant and its moons send out radio waves.

Objects in the Milky Way

  • Supernova remnants
  • Pulsars
  • The Galactic Center

Objects outside the Milky Way

  • Quasars
  • Seyfert galaxies

Collision with radio services

Radio astronomy analyzes of extremely weak signals. -260 DBm as received signal strength are not uncommon. Other radio services can mask or interfere with the interest to the radio astronomy signals easily, so that an evaluation is no longer possible.

Radio astronomy is declared by the ITU as "passive service", as the spectra are assigned as all other radio users. These bands allocated, however, are relatively limited and are also always in the interest of other radio services must therefore be defended in the context of regulatory processes. But radio astronomers also use spectral regions that are indeed reserved for active radio services but are rarely used or used locally restricted. The ever- growing hunger of the economy after bands for active radio services such as data networks and telecommunications, however, limited in the non-reserved bands, the use of radio astronomy ever. Add the reserved bands turn to radio astronomers are faced with increasing unwanted interference caused by faulty transceiver and poorly designed transmitter. The total number of faults is increasing worldwide.

Since the radio astronomy is but interested in getting weaker signals from space, eg be able to detect the presence of organic molecules, experts speak of a closing window into space. More and more bands are no longer available, or the strategies to detect faults and to remove from the useful signal can be more complex.

Some scientists see especially critical as the only way to permanently exploring further parts of the universe a telescope station on the opposite side of the earth the moon.

Significant radio observatories

  • IRAM 30 m
  • Very Large Array
  • Selentschukskaja
  • Westerbork
  • Arecibo
  • Jodrell Bank
  • Astropeiler
  • Radio Telescope Effelsberg
  • Astrophysical Institute Potsdam (AIP )
  • Atacama Large Millimeter Array ( ALMA)
  • Large Millimeter Telescope
Yagi-Uda antenna Helical antenna Goldstone Deep Space Communications Complex Radio galaxy International Telecommunication Union Westerbork (village) Arecibo Observatory Jodrell Bank Observatory Effelsberg 100-m Radio Telescope National Radio Astronomy Observatory Radar astronomy Visible-light astronomy Ultraviolet astronomy Gamma-ray astronomy Integrated Authority File
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