Arp 220
| Galaxy Arp 220 / APG 220 |
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| The galaxy Arp 220 imaged using the Hubble Space Telescope | |
| AladinLite | |
| Constellation | Snake |
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Position equinox : J2000.0 , epoch : J2000.0 |
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| Right ascension | 15 h 34 m 57.2 s |
| declination | + 23 ° 30 ′ 11 ″ |
| Appearance | |
| Morphological type | S?; LINER; HII Sy2 |
| Brightness (visual) | 13.4 mag |
| Brightness (B-band) | 14.0 mag |
| Angular expansion | 1.8 ′ × 1.7 ′ |
| Position angle | 144 ° |
| Surface brightness | 14.5 mag / arcmin² |
| Physical data | |
| Redshift | 0.018126 ± 0.000023 |
| Radial velocity | (5434 ± 7) km / s |
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Stroke distance v rad / H 0 |
(247 ± 17) · 10 6 ly (75.7 ± 5.3) Mpc |
| history | |
| discovery | Truman Safford |
| Discovery date | May 4, 1866 |
| Catalog names | |
| IC 1127/4553 • UGC 9913 • PGC 55497 • CGCG 136-017 • MCG + 04-37-005 • Arp 220 • VV 540 • | |
Arp 220 , also known as APG 220, is the example of an ultra- luminous infrared galaxy that is closest to earth , with more than 10 12 solar luminosities . It is about 247 million light years away. The object was discovered on May 4, 1866 by Truman Henry Safford .
Halton Arp organized his catalog of unusual galaxies into groups according to purely morphological criteria. This galaxy belongs to the class of galaxies with adjacent loops . Weak loops and arms in deep optical images next to the actual galaxy suggest that it was created by merging two galaxies. The Arp 220 was recognized as exceptional in the 1980s by measurements with the IRAS infrared telescope . Their luminosity is much greater than in normal galaxies and mostly escapes in the far infrared - almost a hundred times more at wavelengths around 100 µm than in blue light at 0.5 µm. The core area of Arp 220 is covered by dust, which swallows the luminosity of its actual energy source and emits it again in the far infrared.
In the visible image of the Hubble Space Telescope , the core area of Arp 220 is completely hidden behind thick streaks of dust. However, many young, bright star clusters also indicate unusual properties here. The near-infrared image of the Hubble Space Telescope penetrates the dust better and shows the not yet fully merged core regions of the two parent galaxies. Even here, however, the regions that are deepest embedded in the dust are not yet visible. Investigations with the Infrared Space Observatory in the mid-infrared and with VLBI in the radio range show that they contain a violent starburst , but a contribution from an active galactic core cannot be ruled out either.
Individual evidence
Web links
literature
- Jeff Kanipe and Dennis Webb: The Arp Atlas of Peculiar Galaxies - A Chronicle and Observer's Guide , Richmond 2006, ISBN 978-0-943396-76-7