NGC 6240
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| Observation data: J2000 epoch | |
|---|---|
| Constellation: | Ophiuchus |
| Right ascension: | 16h 52m 58.9s[1] |
| Declination: | +02° 24′ 03″[1] |
| Redshift: | |
| Distance: | 400 Mly |
| Type: | I0 pec[1] |
| Apparent dimensions (V): | 2'.1 × 1'.1[1] |
| Apparent magnitude (V): | 12.8[1] |
| Notable features: | merger remnant |
| Other designations | |
| IC 4625, UGC 10592, PGC 59186, VV 617[1] | |
| See also: Galaxy, List of galaxies | |
NGC 6240 is a well-studied nearby ultraluminous infrared galaxy (ULIRG) in the constellation Ophiuchus. The galaxy is the remnant of a merger between two smaller galaxies. The collision between the two progenitor galaxies has resulted in a single larger galaxy with two distinct nuclei and a highly disturbed structure, including faint extensions and loops[2].
Contents |
[edit] Double Nuclei
[edit] Star formation versus supermassive black holes
The power sources of ULIRGs in general has been greatly debated. Infrared light from galaxies generally originates from dust in the interstellar medium. ULIRGs are notable in that they are abnormally bright in the infrared. The infrared dust emission in ULIRGs is over one trillion times more luminous than the Sun (i.e. it has an infrared luminosity of 1012 Lʘ). Astronomers have speculated that either intense star formation regions or active galactic nuclei (which contain supermassive black holes) may be responsible for the intense dust heating that produces this emission, although the general consensus is that both may be present in most ULIRGs. Studying the exact nature of ULIRGs has been difficult, however, because the dust in the centers of these galaxies obscures both visible and near-infrared starlight and because theoretical models of both starbursts and active galactic nuclei have demonstrated that they may look similar. Because NGC 6240 is a nearby example of such a ULIRG, astronomers have studied it intensively to understand its power source.
[edit] X-Ray Observations
Observations performed by S. Komossa and collaborators with the Chandra X-Ray Observatory have detected strong hard X-ray emission from both of the nuclei. The intensity of this emission and the presence of emission from highly ionized iron indicate that both of the nuclei are active galactic nuclei[3].
[edit] See also
- Arp 220 - another ultraluminous infrared galaxy and merger remnant
- Antennae Galaxies - a nearby pair of merging galaxies
- NGC 520 - another merger remnant
[edit] References
- ^ a b c d e f NASA/IPAC Extragalactic Database. Results for NGC 6240. Retrieved on 2006-08-16.
- ^ J. W. Fried, H. Schulz (1983). "NGC 6240 - A unique interacting galaxy". Astronomy and Astrophysics 118: 166-170.
- ^ S. Komossa, V. Burwitz, G. Hasinger, P.Predehl, J. S. Kaastra, Y. Ikebe (2003). "Discovery of a Binary Active Galactic Nucleus in the Ultraluminous Infrared Galaxy NGC 6240 Using Chandra". Astrophysical Journal 582: L15-L19.
