Debris disk
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Debris disk is a ring-shaped circumstellar disk of dust and debris in orbit around a star. Debris disks have been found around both evolved and young stars, as well as at least one debris disk in orbit around a neutron star.[1] They can consitute a phase in the formation of a planetary system, thus forming a protoplanetary disk.[2] They can also be produced and maintained as the remnants of collisions between planetismals.[3]
By 2001, over 900 candidate stars have been found to possess a debris disk. They are usually located by examining the star system in infrared light and looking for an excess of radiation beyond that emitted by the star. This excess is inferred to be radiation from the star that has been absorbed by the disk, then radiated away as infrared energy.[4]
In certain cases the debris disks can be observed directly by occulting the primary star and then imaging the system.
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[edit] Observation history
In 1984 a debris disk was located in orbit around the star Vega using the IRAS satellite. Initially this was believed to be a protoplanetary disk, but it is now thought to be a debris disk by reason of the star's relative youth. Subsequently irregularities have been found in the disk, which may be indicative of the presence of planetary bodies.[5] Similar discoveries of debris disks were made around the stars Fomalhaut and Beta Pictoris.
By 1998 a debris disk had been located around the nearby star 55 Cancri, a system that is also known to contain a planet.[6] Structures in the debris disk around Epsilon Eridani also suggest perturbations by a planetary body in orbit around that star, which may be used to constrain the mass and orbit of the planet.[7]
[edit] Origin
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[edit] Notable belts
Belts of dust or debris have also been detected around stars other than the Sun, including the following:
| Star | Distance (ly) |
Orbit (AU) |
|---|---|---|
| Epsilon Eridani[7] | 10.5 | 35-75 |
| Vega[5] | 25 | 86-200 |
| AU Microscopii[8] | 33 | 50–150 |
| HD 69830 | 41 | <1 |
| 55 Cancri[6] | 41 | 27-50 |
| HD 139664 | 57 | 60-109 |
| HD 53143 | 60 | ? |
| Beta Pictoris | 63 | 25-550 |
| Zeta Leporis[9] | 70 | 2.5-12.2 |
| HD 107146 | 88 | 130 |
| Fomalhaut[5] | 133 | 25 |
| HD 12039 | 137 | 5 |
| HR 4796 A | 220 | 200 |
| HD 141569 | 320 | 400 |
| HD 113766 | 430 | 0.35-5.8 |
| HD 92945 |
The orbital distance of the belt is an estimated mean distance or range, based either on direct measurement from imaging or derived from the temperature of the belt. The Earth has an average distance from the Sun of 1 AU.
[edit] References
- ^ Z. Wang, D. Chakrabarty, D. L. Kaplan (2006). "A debris disk around an isolated young neutron star". Nature 440 (7085): 772-775.
- ^ "Spitzer Team Says Debris Disk Could Be Forming Infant Terrestrial Planets", NASA, December 14, 2005. Retrieved on January 3, 2007.
- ^ "Spitzer Sees Dusty Aftermath of Pluto-Sized Collision", NASA, January 10, 2005. Retrieved on January 3, 2007.
- ^ Debris Disk Database. Royal Observatory Edinburgh. Retrieved on January 3, 2007.
- ^ a b c Joint Astronomy Centre (April 21, 1998). Astronomers discover possible new Solar Systems in formation around the nearby stars Vega and Fomalhaut. Press release. Retrieved on 2006-04-24.
- ^ a b "University Of Arizona Scientists Are First To Discover Debris Disk Around Star Orbited By Planet", ScienceDaily, October 23, 1998. Retrieved on May 24, 2006.
- ^ a b J.S. Greaves; W.S. Holland; M.C. Wyatt; W.R.F. Dent; E.I. Robson; I.M. Coulson; T. Jenness; G.H. Moriarty-Schieven; G.R. Davis; H.M. Butner; W.K. Gear; C. Dominik; H. J. Walker (2005). "Structure in the Epsilon Eridani Debris Disk". The Astrophysical Journal 619: L187 – L190.
- ^ Sanders, Robert. "Dust around nearby star like powder snow", UC Berkeley News, January 8, 2007. Retrieved on January 11, 2007.
- ^ M. M. Moerchen, C. M. Telesco, C. Packham, T. J. J. Kehoe (2006). "Mid-infrared resolution of a 3 AU-radius debris disk around Zeta Leporis". Astrophysical Journal Letters.
[edit] See also
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