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File:243 ida.jpg
File:762Pulcova-SwRI.gif

A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. It is thought that many asteroids and Kuiper belt objects may possess moons, in some cases quite substantial in size. Discoveries of minor-planet moons (and binary objects, in general) are important because the determination of their orbits provides estimates on the mass and density of the primary, allowing insights of their physical properties that is generally not otherwise possible.[1] Template:As of, there are over 200 minor planets known to have moons.[2]

TerminologyEdit

In addition to the terms satellite and moon, the term binary is sometimes used for minor planets with moons (or triple for minor planets with two moons). If one object is much bigger it can be referred to as the primary and its companion as secondary. The term double asteroid is sometimes used for systems in which the asteroid and its moon are roughly the same size, while binary tends to be used independently from the relative sizes of the components. When binary minor planets are similar in size, the Minor Planet Center (MPC) refers to them as "binary companions" instead of referring to the smaller body as a satellite.[3] A good example of a true binary is the 90 Antiope system, identified in August 2000.[4] Small satellites are often referred to as moonlets.[1][5]

Discovery milestonesEdit

Template:As of, over 230 moons of minor planets have been discovered.[2] These consist of:

Prior to the era of the Hubble telescope and space probes reaching the outer Solar System, attempts to detect satellites around asteroids were limited to optical observations from Earth. For example, in 1978, stellar occultation observations were claimed as evidence of a satellite for the asteroid 532 Herculina.[7] However, later more-detailed imaging by the Hubble Telescope did not reveal a satellite, and the current consensus is that Herculina does not have a significant satellite.[8] There were other similar reports of asteroids having companions (usually referred to as satellites) in the following years. Also, a letter in Sky & Telescope magazineTemplate:Citation needed at this time pointed to apparently simultaneous impact craters on Earth (for example, the Clearwater Lakes in Quebec), suggesting that these craters were caused by pairs of gravitationally-bound objects.

In 1993, the first asteroid moon was confirmed when the Galileo probe discovered the small Dactyl orbiting 243 Ida in the asteroid belt. The second was discovered around 45 Eugenia in 1998.[9] In 2001, 617 Patroclus and its same-sized companion Menoetius became the first known binary asteroids in the Jupiter Trojans.[10] The first trans-Neptunian binary, Template:Mpl, was optically resolved in 2002.[11]

Triple systemsEdit

In 2005, the asteroid 87 Sylvia was discovered to have two satellites, making it the first known triple asteroid.[12] This was followed by the discovery of a second moon orbiting 45 Eugenia.[13] Also in 2005, the Kuiper belt object (KBO) Template:Dp was discovered to have two moons, making it the second KBO after Pluto known to have more than one moon. Other known triple systems include: 3749 Balam (March 2008),[14] 216 Kleopatra (September 2008),[15] and 93 Minerva (August 2009).[16]

CommonalityEdit

The data about the populations of binary objects are still patchy. In addition to the inevitable observational bias (dependence on the distance from Earth, size, albedo and separation of the components) the frequency appears to be different among different categories of objects. Among asteroids, an estimated 2% would have satellites. Among trans-Neptunian objects (TNO), an estimated 11% are believed to be binary or multiple objects, but three of the four known large TNO (75%) have at least one satellite.

More than 20 binaries are known in each of the main groupings: near-Earth asteroids, main-belt asteroids, and trans-Neptunians, not including numerous claims based solely on light-curve variation.

No binaries have been found so far among centaurs with semi-major axis smaller than Neptune.[17] However, using an extended definition of Centaurs, as the objects on unstable orbits with the perihelion inside the orbit of Neptune, the first binary centaur, 42355 Typhon (previously known as Template:Mp), was identified in 2006.[18]

OriginEdit

The origin of minor-planet moons is not currently known with certainty, and a variety of theories exist. A widely accepted theory is that minor-planet moons are formed from debris knocked off of the primary by an impact. Other pairings may be formed when a small object is captured by the gravity of a larger one.

Formation by collision is constrained by the angular momentum of components i.e. by the masses and their separation. Close binaries fit this model (e.g. PlutoCharon). Distant binaries however, with components of comparable size, are unlikely to have followed this scenario, unless considerable mass has been lost in the event.

The distances of the components for the known binaries vary from a few hundreds of kilometres (243 Ida, 3749 Balam) to more than 3000 km (379 Huenna) for the asteroids. Among TNOs, the known separations vary from 3,000 to 50,000 km.[17]

PopulationsEdit

What is "typical" for a binary system tends to depend on its location in the Solar System (presumably because of different modes of origin and lifetimes of such systems in different populations of minor planets).[19]

  • Among near-Earth asteroids, satellites tend to orbit at distances of the order of 3–7 primary radii, and have diameters two to several times smaller than the primary. Since these binaries are all inner-planet crossers, it is thought that tidal stresses that occurred when the parent object passed close to a planet may be responsible for the formation of many of them, although collisions are thought to also be a factor in the creation of these satellites.
  • Among main-belt asteroids, the satellites are usually much smaller than the primary (a notable exception being 90 Antiope), and orbit around 10 primary radii away. Many of the binary systems here are members of asteroid families, and a good proportion of satellites are expected to be fragments of a parent body whose disruption after an asteroid collision produced both the primary and satellite.
  • Among trans-Neptunian objects, it is common for the two orbiting components to be of comparable size, and for the semi-major axis of their orbits to be much larger − about 100 to 1000 primary radii. A significant proportion of these binaries are expected to be primordial.

Dwarf planetsEdit

Among the dwarf planets, it is 90 percent certain that Template:Dp has no moons larger than 1 km in size, assuming that they would have the same albedo as Ceres itself.[20]

Pluto has five known moons. Its largest moon Charon is more than half the size of Pluto itself, and large enough to orbit a point outside Pluto's surface. In effect, each orbits the other, forming a binary system informally referred to as a double dwarf planet. Pluto's four other moons, Nix, Hydra, Kerberos, and Styx, are far smaller and orbit the Pluto–Charon system.

Haumea has two moons with radii estimated around 155 km (Hiʻiaka) and 85 km (Namaka).

Template:Dp has no known moons. A satellite having 1% Makemake's brightness would have been detected if it had been located at an angular distance from Makemake farther than 0.4 arcseconds (0.0001 degrees; 2 microradians).[21]

Template:Dp has one known moon, Dysnomia. Its radius, based on its brightness, is estimated to be roughly between 150 and 350 km.[22]

List of minor planets with moonsEdit

Near-Earth objectsEdit

File:Asteroid 1994 KW4.jpg
File:1994CC-with-moons.gif
Name Type Diameter (km)
(or dimensions)
Name of moon Diameter of moon (km)
(or dimensions)
Separation (km)
1862 Apollo Apollo 1.7 S/2005 (1862) 1 0.08 3
3671 Dionysus Amor 1.5 S/1997 (3671) 1 0.4 2.2
5381 Sekhmet Aten 1 S/2003 (5381) 1 0.3 1.54 ± 0.12
7088 Ishtar Amor 1.5? S/2006 (7088) 1  ?  ?
(31345) 1998 PG Amor 0.9 S/2001 (31345) 1 0.3 1.5
(35107) 1991 VH Apollo 1.2 S/2001 (35107) 1 0.5 3.2
65803 Didymos Amor 0.8 S/2003 (65803) 1 0.15 ± 0.05 1.1
Template:Mpl Aten 0.9 S/2001 (66063) 1 0.36 0.8
Template:Mpl Aten 1.2 S/2001 (66391) 1 0.45 ± 0.03 2.6
69230 Hermes Apollo 0.4 S/2003 (69230) 1 0.4 1
Template:Mpl Apollo 0.7 S/2004 (85938) 1 0.35 1.5
Template:Mpl Apollo 1 S/2001 (88710) 1 0.31 1.8
Template:Mpl Amor 2.6 2 moons: Gamma (inner), Beta (outer)  ? 3.8, 16.6
(136617) 1994 CC Apollo 0.7 2 moons: Beta (inner), Gamma (outer)  ? 1.7, 6.1
Template:Mpl Aten 3.5 Template:Mpl 0.8 7.0
(162000) 1990 OS Apollo 0.3 S/2003 (1990 OS) 1 0.045 0.6
(164121) 2003 YT1 Apollo 1 Template:Mp 0.18 ~2.7
(175706) 1996 FG3 Apollo 1.4 Template:Mp 0.43 2.4
(185851) 2000 DP107 Apollo 0.80 (± 0.16) Template:Mp 0.30 (± 0.15) 2.622 ± 0.162
Template:Mpl Amor 2.75 S/2013 (285263) 1 0.6  ?
Template:Mpl Amor 0.9 Template:Mp 0.5 2.1
1994 XD Apollo 1? Template:Mp  ?  ?
Template:Mpl Aten 0.8 Template:Mp 0.12 4.5 ± 0.5
Template:Mpl Apollo 0.23 ± 0.06 Template:Mp 0.10 0.337 ± 0.013
Template:Mpl Amor 0.6 Template:Mp 0.1 1.5
Template:Mpl Apollo 3 Template:Mp 0.2 5
Template:Mpl Amor 0.5 Template:Mp 0.1  ?
Template:Mpl Apollo 0.12 Template:Mp 0.06 0.3?
(311066) 2004 DC Apollo 0.3 Template:Mp  ?  ?
2005 AB Amor 1.2? Template:Mp 0.3 2.5?
Template:Mpl Apollo 0.5 ± 0.1 Template:Mp 0.2 ± 0.1 ≥ 0.6
Template:Mpl Apollo 0.45 Template:Mp  ?  ?

Mars crossersEdit

Name Diameter (km)
(or dimensions)
Name of moon Diameter of moon (km)
(or dimensions)
Separation (km)
1139 Atami 7 S/2005 (1139) 1 5 15?
2044 Wirt 7 S/2006 (2044) 1 2  ?
(5407) 1992 AX 4 S/2001 (5407) 1 1.2 6.8
Template:Mpl 4? S/2005 (34706) 1 1? 8?
Template:Mpl 3? S/2005 (114319) 1  ?  ?

Main-belt asteroidsEdit

Name Diameter (km)
(or dimensions)
Name of moon Diameter of moon (km)
(or dimensions)
Separation (km)
22 Kalliope (215×180×150) Linus 38 ± 6 1,065 ± 8
41 Daphne (239x183x153) S/2008 (41) 1 <2 443
45 Eugenia (305×220×145) Petit-Prince (Eugenia I) 13 ± 1 1,184 ± 12
Template:Mpl ~6 ~700(?)
87 Sylvia (385×265×230) Remus (Sylvia II) 7 ± 2 706 ± 5
Romulus (Sylvia I) 18 ± 4 1,356 ± 5
90 Antiope 110±16 S/2000 (90) 1 110 ± 16 170 ± 1
93 Minerva 140 Aegis (Minerva I) 4 630?
Gorgoneion (Minerva II) 3 380?
107 Camilla (285×205×170) ± 20 S/2001 (107) 1 11 ± 2 1,235 ± 16
121 Hermione (254×125) S/2002 (121) 1 12 ± 4 768 ± 11
130 Elektra (215×155) S/2003 (130) 1 6 ± 2 1,252 ± 30
216 Kleopatra 217×94×81 Alexhelios (Kleopatra I) 5 650
Cleoselene (Kleopatra II) 3 380
243 Ida (59.8×25.4×18.6) Dactyl (Ida I) (1.6×1.4×1.2) 108
283 Emma 148.1 ± 4.6 S/2003 (283) 1 12 596 ± 3
379 Huenna 92.3 ± 1.7 S/2003 (379) 1 7 3,400 ± 11
702 Alauda 194.73 ± 3.2 S/2007 (702) 1 5.5 900
762 Pulcova 137.1 ± 3.2 S/2000 (762) 1 20 810
809 Lundia ~7–10 S/2005 (809) 1 ~7–10 ~10–20
854 Frostia 13.7 ± 5.6 S/2004 (854) 1 10 ~25
1089 Tama 12.9 S/2003 (1089) 1 9 20
1313 Berna 11 S/2004 (1313) 1 11 35
1338 Duponta 8–19 S/2007 (1338) 1 ~3?  ?
1509 Esclangona 12 S/2003 (1509) 1 4 140
1717 Arlon 9? S/2006 (1717) 1  ? 18?
2006 Polonskaya 10 S/2005 (2006) 1  ?  ?
2478 Tokai 10? S/2007 (2478) 1 7?  ?
2486 Metsähovi[23] 12? S/2007 (2486) 1  ?  ?
2754 Efimov 7? S/2006 (2754) 1  ? 12?
3073 Kursk 8? S/2007 (3073) 1  ?  ?
3309 Brorfelde 6? S/2005 (3309) 1  ?  ?
3703 Volkonskaya 3 S/2003 (3703) 1 1.2  ?
3749 Balam 7 S/2002 (3749) 1 1.5 310 ± 20
S/2008 (3749) 1 3 ~20
3782 Celle 6 S/2003 (3782) 1 2.5 30
3982 Kastel  ? S/2005 (3982) 1  ?  ?
4029 Bridges 10 S/2006 (4029) 1  ?  ?
4492 Debussy 10 S/2004 (4492) 1  ? 25
4674 Pauling 8 S/2004 (4674) 1 2.5 250
4786 Tatianina 8? S/2006 (4786) 1  ?  ?
5477 Holmes ~7 S/2005 (5477) 1 2.5 15
5905 Johnson 5 S/2005 (5905) 1 2  ?
6084 Bascom 9? S/2006 (6084) 1 3.5? 32?
6244 Okamoto 7? S/2006 (6244) 1 1.7? 15?
9069 Hovland 3 S/2004 (9069) 1 0.9  ?
9260 Edwardolson ~4 S/2005 (9260) 1  ?  ?
9617 Grahamchapman 5? S/2006 (9617) 1 1.4?  ?
11264 Claudiomaccone 4 S/2003 (11264) 1 1.2  ?
Template:Mpl 4.5 S/2004 (17246) 1 2 ~230
Template:Mpl 6? S/2006 (17260) 1 1.5? 10?
Template:Mpl 4.5 S/2003 (22899) 1 1.5 ~170
Template:Mpl 3.6 S/2005 (76818) 1 1.1  ?

Jupiter trojansEdit

Name Diameter (km)
(or dimensions)
Name of moon Diameter of moon (km)
(or dimensions)
Separation (km)
617 Patroclus 121.8 ± 3.2 Menoetius (Patroclus I) 112.6 ± 3.2 685 ± 40
624 Hektor (363×207) S/2006 (624) 1 15 1,000?

Trans-Neptunian objectsEdit

Name Type Diameter (km)
(or dimensions)
Name of moon Diameter of moon (km)
(or dimensions)
Separation (km)
134340 Pluto Plutino 2306 ± 20 Charon (Pluto I) 1207 ± 3 19,571 ± 4
Styx (Pluto V) 10-25 42,000 ± 2000
Nix (Pluto II) 46-137 48,675 ± 120
Kerberos (Pluto IV) 13–34 59,000 ± 2,000
Hydra (Pluto III) 61-167 64,780 ± 90
Template:Mpl Plutino 221? S/2001 (26308) 1 88 11,310 ± 110
42355 Typhon SDO 134 Echidna (Typhon I) 78 1,300?
Template:Mpl Plutino A1=286 Template:±
A2=265 Template:±
S/2001 (47171) 1 139 Template:± 7411 ± 12
Template:Mpl SDO 352 S/2002 (48639) 1 161 420
50000 Quaoar Cubewano <1100 Weywot (Quaoar I) 96?  ?
Template:Mpl Cubewano 649 S/2007 (55637) 1 205  ?
58534 Logos Cubewano 80 Zoe (Logos I) 66 8,010 ± 80
Template:Mpl SDO 150? S/2006 (60458) 1 119? 2,200?
Template:Mpl 2:5 resonance 151? S/2007 (60621) 1 115? 1,200
65489 Ceto SDO 172 Phorcys (Ceto I) 134 1,840
66652 Borasisi Cubewano 166 Pabu (Borasisi I) 137 4,660 ± 170
79360 Sila–Nunam Cubewano 305 S/2005 (79360) 1 292 2300
Template:Mpl Cubewano 224 S/2005 (80806) 1 129 2700
Template:Mpl SDO 431 S/2005 (82075) 1 237 1900
88611 Teharonhiawako Cubewano 176 ± 20 Sawiskera (Teharonhiawako I) 122 ± 14 27,300 ± 343
90482 Orcus Plutino 946 Vanth (Orcus I) 262 ± 170 8,700
Template:Mpl 1:2 resonance 420? S/2007 (119979) 1  ?  ?
120347 Salacia Cubewano 580? Actaea (Salacia I) 190? 3,500?
Template:Mpl Cubewano 221? S/2007 (123509) 1  ?  ?
Template:Mpl Cubewano 253? S/2003 (134860) 1 175? 2,300?
136108 Haumea Cubewano 1400 Hiʻiaka (Haumea I) 310 49,500 ± 400
Namaka (Haumea II) 170 39,300
136199 Eris SDO 2326 Dysnomia (Eris I) 150–250 30,000–36,000
Template:Mpl Plutino 171? S/2004 (139775) 1 171? 240?
148780 Altjira Cubewano 340? S/2007 (148780) 1 246? 5,800?
174567 Varda cubewano 690? Ilmarë (Varda I) 350? 4,200
(182933) 2002 GZ31 SDO 187? Template:Mp 118? ~2,060 ± 270
(208996) 2003 AZ84 Plutino 686 Template:± Template:Mp 68 ± 20 7,200
385446 Manwë 4:7 resonance ≈140 Thorondor (Manwë I) ≈70 6674 ± 41
Template:Mpl Cubewano 133 ± 15 Template:Mpl 110 ± 12 22,300 ± 800
Template:Mpl Cubewano? 168 Template:Mp 93 2,200
Template:Mpl Cubewano 120? Template:Mp  ? 3,300?
Template:Mpl Cubewano 170 Template:Mp 120 23,000
Template:Mpl Cubewano 164? Template:Mp 133 5,880 ± 200
Template:Mpl Cubewano? 176? Template:Mp 176? 7,000?
Template:Mpl Cubewano 144? Template:Mp 100? 1,900?
Template:Mpl Cubewano 282? Template:Mp 233? 2,800?
Template:Mpl Cubewano 201? Template:Mp 192? 1,400?
Template:Mpl Cubewano 189 Template:Mp 155 3,690 ± 70
Template:Mpl Cubewano 86 Template:Mp 86 ~130,000
385446 Manwë Plutino 265? Template:Mp  ? 10,000?
Template:Mpl SDO 196 Template:Mp 178 10,000
Template:Mpl Cubewano 127 Template:Mp 97 60,000
Template:Mpl Cubewano 210? Template:Mp 121? 5,400
Template:Mpl Cubewano 240 Template:Mp  ? 85,000

See also Edit

References Edit

  1. 1.0 1.1 Dr. William J. Merline and Maria Martinez (2000-10-26). Astronomers Image Double Asteroid. SwRI Press Release. Retrieved on 2009-10-20. (mentions both 90 Antiope and 762 Pulcova)
  2. 2.0 2.1 2.2 Wm. Robert Johnston (2009-10-16). Asteroids with Satellites. Johnston's Archive. Retrieved on 2009-10-20.
  3. Satellites and Companions of Minor Planets. IAU / Minor Planet Center (2009-09-17). Retrieved on 2011-01-08.
  4. 90 Antiope: Raw Keck Image. SWrI Press Release (August 2000). Retrieved on 2009-10-20.
  5. IAUC 8732: S/2006 (624) 1. Retrieved on 2011-01-08. (Satellite Discovery)
  6. Marchis, F. (2008). Multiple Asteroid Systems: New Techniques to Study New Worlds. Lunar and Planetary Institute. Retrieved on 2009-10-20.
  7. Satellite of Minor Planet 532 Herculina Discovered During Occultation. David W. Dunham, The Minor Planet Bulletin, Volume 6, p.13–14 (December 1978) ADS archive copy
  8. Storrs, Alex Weiss; Zellner; Burleson; Sichitiu; Wells; Kowal; Tholen (1999). "Imaging observations of asteroids with Hubble Space Telescope". Icarus 137 (2): 260–268. DOI:10.1006/icar.1999.6047.
  9. Astronomers Discover Moon Orbiting Asteroid. SwRI (1998). Retrieved on 2009-10-21. (Eugenia AO image)
  10. Merline, W. J. (2001). IAUC 7741: 2001fc; S/2001 (617) 1; C/2001 T1, C/2001 T2.
  11. Chiang, E.; Lithwick, Y.; Buie, M.; Grundy, W.; Holman, M.; A Brief History of Trans-Neptunian Space, to appear in Protostars and Planets V (August 2006) Final preprint on arXiv
  12. Daniel W. E. Green (2005-08-11). IAUC 8582: Sats OF (87). International Astronomical Union Circular. Retrieved on 2011-01-08.
  13. Daniel W. E. Green (2007-03-07). IAUC 8817: S/2004 (45) 1. International Astronomical Union Circular. Retrieved on 2011-01-08.
  14. Franck Marchis (Principal Investigator, SETI Institute, UC Berkeley). Franck Marchis Web Page. Department of Astronomy (University of California at Berkeley). Retrieved on 2009-10-27.
  15. Franck Marchis (Principal Investigator, SETI Institute, UC Berkeley) (2008-09-19). Two Companions Found Near Dog-Bone Asteroid. SETI Institute. Retrieved on 2009-10-26.
  16. Franck Marchis (2009-08-21). The discovery of a new triple asteroid – (93) Minerva. Cosmic Diary Blog. Retrieved on 2009-10-27.
  17. 17.0 17.1 Noll, Keith S. "Solar System binaries", Asteroids, Comets, Meteors, Proceedings of the 229th Symposium of the IAU, Rio de Janeiro, 2005, Cambridge University Press, 2006., pp. 301–318 Preprint
  18. K. Noll, H. Levison W. Grundy, D. Stephens (October 2006). "Discovery of a binary Centaur". Icarus 184. DOI:10.1016/j.icarus.2006.05.010.
  19. "T. Michałowski et al. (2004). "Eclipsing binary asteroid 90 Antiope". Astronomy & Astrophysics 423 (3): 1159. DOI:10.1051/0004-6361:20040449.
  20. Bieryla, Allyson (December 2006). "Search for Satellites around Ceres". 2007 AAS/AAPT Joint Meeting, American Astronomical Society Meeting 209, #25.02; Bulletin of the American Astronomical Society 38: 933.
  21. Template:Cite doi
  22. Template:Cite arXiv
  23. http://www.cbat.eps.harvard.edu/cbet/000800/CBET000860.txt CBET 860
  • Asteroids with Satellites web page, maintained up to date by W. Robert Johnston; and references therein. (last accessed 13-03-2007)
  • The VOBAD database a web page built and designed by F. Marchis and his collaborators (UC-Berkeley/SETI Institute) which contains the parameters of 169 multiple asteroid systems (last update May 9, 2009)

External links Edit

Template:Asteroids Template:Small Solar System bodies Template:Solar System moons (compact) Template:Solar System

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