DEBRIS DISK

'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 constitute 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.

Contents

Observation history

Origin

Known belts

See also

References

External link

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]

Origin

Typical debris disks contain small grains 1–100 μm in size. Radiation from the host star can cause cause these particles to spiral inward because of the Poynting-Robertson effect, so the lifetime of the disk will be on the order of 10 Myr or less. Thus, for a disk to remain intact, a process is needed to continually replentish the disk. This can occur, for example, by means of collisions between larger bodies. This can occur on a continual basis as collisions grind objects down into ever smaller bodies.^[8]
For collisions to occur in a debris disk, the bodies must be gravitationally perturbed sufficiently to create relatively large collisional velocities. A planetary system around the star can cause such perturbations, as can a binary star companion or the close approach of another star.

Known belts

Belts of dust or debris have also been detected around stars other than the Sun, including the following:

Star	Spectral class[9]	Distance (ly)	Orbit (AU)
Epsilon Eridani7	K2V	10.5	35–75
Vega5[10]	A0V	25	86–200
AU Microscopii 33	50–150
HD 69830[11]	K0V	41	<1
55 Cancri A6	G8V	41	27–50
HD 139664[12]	F5IV-V	57	60–109
Eta Corvi[13]	F2V	59	100–150
HD 5314312	K1V	60	?
Beta Pictoris10	A5V	63	25–550
Zeta Leporis[14]	A2Vann	70	2.5–12.2
HD 92945[15]	K1V	72	45–175
HD 107146[16]	G2V	88	130
Fomalhaut5	A3V	133	25
HD 12039[17]	G3-5V	137	5
HD 15115[18]	F2V	150	315–550
HR 4796 A[19][20]	A0V	220	200
HD 14156920	B9.5e	320	400
HD 113766 A[21]	F4V	430	0.35–5.8

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.

See also

★ Accretion disc

★ Asteroid belt

★ Kuiper belt

References

1. A debris disk around an isolated young neutron star, Z. Wang, D. Chakrabarty, D. L. Kaplan, , , Nature, 2006
2. Spitzer Team Says Debris Disk Could Be Forming Infant Terrestrial Planets
3. Spitzer Sees Dusty Aftermath of Pluto-Sized Collision
4. Debris Disk Database
5.
6. University Of Arizona Scientists Are First To Discover Debris Disk Around Star Orbited By Planet
7. Structure in the Epsilon Eridani Debris Disk, 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, , , The Astrophysical Journal, 2005
8. Stellar Flybys & Planetary Debris Disks Scott Kenyon & Benjamin Bromley
9. SIMBAD: Query by identifiers
10. Dust in beta PIC / VEGA Main Sequence Systems, , D. E., Backman, Bulletin of the American Astronomical Society, 1996
11. On the Nature of the Dust in the Debris Disk around HD 69830, Lisse, C. M.; Beichman, C. A.; Bryden, G.; Wyatt, M. C., , , The Astrophysical Journal, 1999
12. First Scattered Light Images of Debris Disks around HD 53143 and HD 139664, Kalas, Paul; Graham, James R.; Clampin, Mark C.; Fitzgerald, Michael P., , , The Astrophysical Journal, 2006
13. Submillimeter Images of a Dusty Kuiper Belt around Corvi, Wyatt, M. C.; Greaves, J. S.; Dent, W. R. F.; Coulson, I. M., , , The Astrophysical Journal, 2005
14. Mid-infrared resolution of a 3 AU-radius debris disk around Zeta Leporis, M. M. Moerchen, C. M. Telesco, C. Packham, T. J. J. Kehoe, , , Astrophysical Journal Letters, 2006
15. Observations and Models of the Debris Disk around K Dwarf HD 92945 D. Golimowski ''et al''
16. Detection of cool dust around the G2V star HD 107146, Jonathan P. Williams ''et al'', , , Astrophysical Journal, 2004
17. The Formation and Evolution of Planetary Systems (FEPS): Discovery of an Unusual Debris System Associated with HD 12039, Hines, Dean C. ''et al'', , , The Astrophysical Journal, 2006
18. Discovery of Extreme Asymmetry in the Debris Disk Surrounding HD 15115, Kalas, Paul; Fitzgerald, Michael P.; Graham, James R., , , The Astrophysical Journal, 2007
19. Mid-Infrared Imaging of a Circumstellar Disk around HR 4796: Mapping the Debris of Planetary Formation, Koerner, D. W.; Ressler, M. E.; Werner, M. W.; Backman, D. E., , , Astrophysical Journal Letters, 1998
20. Hubble Views of Dust Disks and Rings Surrounding Young Stars Yield Clues Villard, Ray; Weinberger, Alycia; Smith, Brad
21. Belt of Material Around Star May Be First Step in Terrestrial Planet Formation

External link

★ Catalog of Resolved Circumstellar Disks