Arp 220

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Arp 220
Observation data (J2000 epoch)
Constellation Serpens
Right ascension 15h 34m 57.1s[1]
Declination +23° 30′ 11″[1]
Redshift 5434 ± 7 km/s[1]
Distance 250 Mly (77 Mpc)[citation needed]
Type S?[1]
Apparent dimensions (V) 1′.5 x 1′.2[1]
Apparent magnitude (V) 13.9[1]
Other designations
IC 1127,[1] IC 4553,[1]
UGC 9913,[1] PGC 55497[1]
See also: Galaxy, List of galaxies

Arp 220 is the result of a collision between two galaxies which are now in the process of merging. Located 250 million light-years away in the constellation Serpens, it is the 220th object in Halton Arp's Atlas of Peculiar Galaxies.

[edit] Features

It is the closest Ultraluminous Infrared Galaxy (ULIRG) to Earth, with its energy output dominated by the far-infrared part of the spectrum. It is often regarded as the prototypical ULIRG and is the subject of much study as a result. Recent (2002 and 1997) observations of Arp 220, taken in visible light with Advanced Camera for Surveys and in infrared light with Near Infrared Camera and Multi-Object Spectrometer (both instruments on Hubble Space Telescope), revealed more than 200 huge star clusters in central part of the galaxy. The heftiest Arp 220 clusters contains enough material to equal about 10 million suns.[2]. X-ray observations by the Chandra and XMM-Newton satellites have shown that Arp 220 probably includes an Active Galactic Nucleus (AGN) at its core. This raises interesting questions about the link between galaxy mergers and AGN. Another nearby galaxy merger, NGC 6240, has been shown to contain two AGN that will presumably merge at some point in the future. However, despite the presence of the AGN in Arp 220, most of its energy output is thought to be the result of a massive burst of star formation, or starburst, thought to have been triggered by the merging of the two galaxies.

Far-infrared luminous objects like Arp 220 have been found in surprisingly large numbers by sky surveys of Submillimetre wavelengths using instruments such as Submillimetre Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT). Arp 220 and other local ULIRGs are being studied as local equivalents of this kind of object.

Astronomers from the Arecibo Observatory have detected organic molecules in the galaxy.[3]

Arp 220 contains two nuclei, an OH megamaser, and a water maser.[4]

[edit] External links

[edit] References

  1. ^ a b c d e f g h i j NASA/IPAC Extragalactic Database. Results for Arp 220. Retrieved on 2006-12-07.
  2. ^ Hubble Eyes Star Birth in the Extreme. Retrieved on 2006-10-16.
  3. ^ "Arecibo telescope finds critical ingredients for the soup of life in a galaxy far, far away", Cornell Chronicle, Cornell University, 2008-01-14. Retrieved on 2008-04-01. 
  4. ^ SIMBAD Astronomical Database. Results for Arp 220. Retrieved on 2006-12-07.
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