Asteroid family

Asteroid families become visible as distinct concentrations when asteroids are plotted in the proper orbital element space (ip vs ap). Some prominent families are the Vesta, Eunomia, Koronis, Eos, and Themis family located in different (colorized) regions of the asteroid belt.

An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An asteroid family is a more specific term than asteroid group whose members, while sharing some broad orbital characteristics, may be otherwise unrelated to each other.

General properties

Plot of proper inclination vs. eccentricity for numbered asteroids

Large prominent families contain several hundred recognized asteroids (and many more smaller objects which may be either not-yet-analyzed, or not-yet-discovered). Small, compact families may have only about ten identified members. About 33% to 35% of asteroids in the main belt are family members.

There are about 20 to 30 reliably recognized families, with several tens of less certain groupings. Most asteroid families are found in the main asteroid belt, although several family-like groups such as the Pallas family, Hungaria family, and the Phocaea family lie at smaller semi-major axis or larger inclination than the main belt.

One family has been identified associated with the dwarf planet Haumea.[1] Some studies have tried to find evidence of collisional families among the trojan asteroids, but at present the evidence is inconclusive.

Origin and evolution

The families are thought to form as a result of collisions between asteroids. In many or most cases the parent body was shattered, but there are also several families which resulted from a large cratering event which did not disrupt the parent body (e.g. the Vesta, Pallas, Hygiea, and Massalia families). Such cratering families typically consist of a single large body and a swarm of asteroids that are much smaller. Some families (e.g. the Flora family) have complex internal structures which are not satisfactorily explained at the moment, but may be due to several collisions in the same region at different times.

Due to the method of origin, all the members have closely matching compositions for most families. Notable exceptions are those families (such as the Vesta family) which formed from a large differentiated parent body.

Asteroid families are thought to have lifetimes of the order of a billion years, depending on various factors (e.g. smaller asteroids are lost faster). This is significantly shorter than the Solar System's age, so few if any are relics of the early Solar System. Decay of families occurs both because of slow dissipation of the orbits due to perturbations from Jupiter or other large bodies, and because of collisions between asteroids which grind them down to small bodies. Such small asteroids then become subject to perturbations such as the Yarkovsky effect that can push them towards orbital resonances with Jupiter over time. Once there, they are relatively rapidly ejected from the asteroid belt. Tentative age estimates have been obtained for some families, ranging from hundreds of millions of years to less than several million years as for the compact Karin family. Old families are thought to contain few small members, and this is the basis of the age determinations.

It is supposed that many very old families have lost all the smaller and medium-sized members, leaving only a few of the largest intact. A suggested example of such old family remains are the 9 Metis and 113 Amalthea pair. Further evidence for a large number of past families (now dispersed) comes from analysis of chemical ratios in iron meteorites. These show that there must have once been at least 50 to 100 parent bodies large enough to be differentiated, that have since been shattered to expose their cores and produce the actual meteorites (Kelley & Gaffey 2000).

Identification of members, interlopers and background asteroids

When the orbital elements of main belt asteroids are plotted (typically inclination vs. eccentricity, or vs. semi-major axis), a number of distinct concentrations are seen against the rather uniform distribution of non-family background asteroids. These concentrations are the asteroid families (see above). Interlopers are asteroids classified as family members based on their so-called proper orbital elements but having spectroscopic properties distinct from the bulk of the family, suggesting that they, contrary to the true family members, did not originate from the same parent body that once fragmented upon a collisional impact.

Description

Comparison: osculating Keplerian orbital elements on the left (families indistinguishable) vs. proper elements on the right (families visible).

Strictly speaking, families and their membership are identified by analysing the proper orbital elements rather than the current osculating orbital elements, which regularly fluctuate on timescales of tens of thousands of years. The proper elements are related constants of motion that remain almost constant for at least tens of millions of years, and perhaps longer.

The Japanese astronomer Kiyotsugu Hirayama (1874–1943) pioneered the estimation of proper elements for asteroids, and first identified several of the most prominent families in 1918. In his honor, asteroid families are sometimes called Hirayama families. This particularly applies to the five prominent groupings discovered by him.

Hierarchical clustering method

Present day computer-assisted searches have identified more than a hundred asteroid families. The most prominent algorithms have been the hierarchical clustering method (HCM), which looks for groupings with small nearest-neighbour distances in orbital element space, and wavelet analysis, which builds a density-of-asteroids map in orbital element space, and looks for density peaks.

The boundaries of the families are somewhat vague because at the edges they blend into the background density of asteroids in the main belt. For this reason the number of members even among discovered asteroids is usually only known approximately, and membership is uncertain for asteroids near the edges.

Additionally, some interlopers from the heterogeneous background asteroid population are expected even in the central regions of a family. Since the true family members caused by the collision are expected to have similar compositions, most such interlopers can in principle be recognised by spectral properties which do not match those of the bulk of family members. A prominent example is 1 Ceres, the largest asteroid, which is an interloper in the family once named after it (the Ceres family, now the Gefion family).

Spectral characteristics can also be used to determine the membership (or otherwise) of asteroids in the outer regions of a family, as has been used e.g. for the Vesta family, whose members have an unusual composition.

Family types

As previously mentioned, families caused by an impact that did not disrupt the parent body but only ejected fragments are called cratering families. Other terminology has been used to distinguish various types of groups which are less distinct or less statistically certain from the most prominent "nominal families" (or clusters).

Clusters, clumps, clans and tribes

The term cluster is also used to describe a small asteroid family, such as the Karin cluster.[2] Clumps are groupings which have relatively few members but are clearly distinct from the background (e.g. the Juno clump). Clans are groupings which merge very gradually into the background density and/or have a complex internal structure making it difficult to decide whether they are one complex group or several unrelated overlapping groups (e.g. the Flora family has been called a clan). Tribes are groups that are less certain to be statistically significant against the background either because of small density or large uncertainty in the orbital parameters of the members.

List

Prominent families

Nysa familyVesta familyFlora familyEos familyKoronis familyEunomia familyHygiea familyThemis familyHungaria familyAsteroid family#All familiesAsteroid beltCircle frame.svg
  •   Nysa: 19,073 (4.8%)
  •   Vesta: 15,252 (3.8%)
  •   Flora: 13,786 (3.5%)
  •   Eos: 9,789 (2.5%)
  •   Koronis: 5,949 (1.5%)
  •   Eunomia: 5,670 (1.4%)
  •   Hygiea: 4,854 (1.2%)
  •   Themis: 4,782 (1.2%)
  •   Hungaria: 2,965 (0.7%)
  •   All other families: 21,500 (5.4%)
  •   Background: 295,000 (74.0%)
Distribution of the most prominent families, other families and background asteroids (up to number 398,000)[3]: 23 

Among the many asteroid families, the Eos, Eunomia, Flora, Hungaria, Hygiea, Koronis, Nysa, Themis and Vesta families are the most prominent ones in the asteroid belt. For a complete list, see § All families.

Eos family
The Eos family (adj. Eoan; 9,789 members, named after 221 Eos)
Eunomia family
The Eunomia family (adj. Eunomian; 5,670 known members, named after 15 Eunomia) is a family of S-type asteroids. It is the most prominent family in the intermediate asteroid belt and the 6th-largest family with approximately 1.4% of all main belt asteroids.[3]: 23 
Flora family
The Flora family (adj. Florian; 13,786 members, named after 8 Flora) is the 3rd-largest family. Broad in extent, it has no clear boundary and gradually fades into the surrounding background population. Several distinct groupings within the family, possibly created by later, secondary collisions. It has also been described as an asteroid clan.
Hungaria family
The Hungaria family (adj. Hungarian; 2,965 members, named after 434 Hungaria)
Hygiea family
The Hygiea family (adj. Hygiean; 4,854 members, named after 10 Hygiea)
Koronis family
The Koronis family (adj. Koronian; 5,949 members, named after 158 Koronis)
Nysa family
The Nysa family (adj. Nysian; 19,073 members, named after 44 Nysa). Alternatively named Hertha family after 135 Hertha.
Themis family
The Themis family (adj. Themistian; 4,782 members, named after 24 Themis)
Vesta family
The Vesta family (adj. Vestian; 15,252 members, named after 4 Vesta)

All families

In 2015, a study identified 122 notable families with a total of approximately 100,000 member asteroids, based on the entire catalog of numbered minor planets, which consisted of almost 400,000 numbered bodies at the time (see catalog index for a current listing of numbered minor planets).[3]: 23  The data has been made available at the "Small Bodies Data Ferret".[4] The first column of this table contains the family identification number or family identifier number (FIN), which is an attempt for a numerical labeling of identified families, independent of their currently used name, as a family's name may change with refined observations, leading to multiple names used in literature and to subsequent confusion.[3]: 17 

FINFamilyLbl# of MembersLoc.
[note 1]
Taxonomymean-
albedo
mean amean emean iParent body · NotesCatLoMP
001Hilda familyHIL409rimC0.043.9650.1748.92153 Hilda; adj. Hildian; within the larger dynamical group with the same name.
(a–e–i: 3.7–4.2 AU; > 0.07; < 20°)
catlist
002Schubart familySHU352rimC0.033.9660.1912.921911 Schubart (within the dynamical Hilda group)catlist
003Hungaria familyH2965closeE0.351.9440.07820.87434 Hungaria; located within the dynamical group of the same name.
(a–e–i: 1.78–2.0 AU; < 0.18; 16°–34°)
catlist
004Hektor familyHEK12trojan5.2040.05419.02624 Hektor (Jupiter trojan)catlist
005Eurybates familyERY218trojanCP0.065.2040.0447.423548 Eurybates (Jupiter trojan)catlist
006unnamed family0067trojan0.065.2040.04931.759799 Thronium (Jupiter trojan)list
007James Bond family[5]0071AASP2.4740.1296.329007 James Bondlist
008Arkesilaos familyARK37trojan5.2040.0298.8920961 Arkesilaos (Jupiter trojan)catlist
009Ennomos familyENM30trojan0.065.2040.04126.794709 Ennomos (Jupiter trojan)catlist
010unnamed family01013trojan0.095.2040.04124.23(247341) 2001 UV209 (Jupiter trojan)list
401Vesta familyV15252AV0.352.3620.0996.364 Vesta (adj. Vestian)catlist
402Flora family
(Ariadne family)
FLO13786AS0.302.2010.1445.348 Flora (adj. Florian), also named after 43 Ariadne; typical asteroid clan. Not a legitimate asteroid family according to Carruba and Milani, instead, the Florian core region is labelled Belgica family and Duponta family (1338), respectively.[6][7]catlist
403Baptistina familyBAP2500AX0.162.2640.1496.00298 Baptistina, merges with the Belgica family (1052) at 100 m/s according to Carruba[7]catlist
404Massalia familyMAS6424AS0.222.4090.1621.4220 Massalia, adj. Massalian, a-e-i: (2.37 to 2.45; 0.12 to 0.21; 0.4 to 2.4)catlist
405Nysa–Polana complex
(Hertha family; Eulalia family)
NYS19073ASFC0.28
0.06
2.4230.1743.0444 Nysa/142 Polana also known as the Hertha family (135 Hertha). Includes the Eulalia family (495 Eulalia)cat(44)
(142)
406Erigone familyERI1776ACX0.062.3670.2104.74163 Erigone, adj. Erigonian. Can be joined with the dynamically different Martes family into a single collisional family (Src).catlist
407Clarissa familyCLA179AX0.052.4060.1073.35302 Clarissacatlist
408Sulamitis familySUL303AC0.042.4630.0915.04752 Sulamitiscatlist
409Lucienne familyLCI142AS0.222.4620.11114.511892 Luciennecatlist
410Euterpe familyEUT474AS0.262.3470.1870.7227 Euterpecatlist
411Datura familyDAT6AS0.212.2350.1565.211270 Datura; Recently formed family with members: (60151), (90265), (203370), (215619) and (338309)catlist
412Lucascavin familyLCA3AS2.2810.1275.2021509 Lucascavin; members: (180255), (209570)catlist
413Klio familyKLI330AC0.072.3620.1939.3884 Kliocatlist
414Chimaera familyCIM108ACX0.062.4600.15514.65623 Chimaeracatlist
415Chaldaea family
(Salli family)
CHL132AC0.072.3760.23611.60313 Chaldaea; alt. named after 1715 Salli by Masierocatlist
416Svea familySVE48ACX0.062.4760.08816.09329 Sveacatlist
417unnamed family4179A2.4650.1533.93(108138) 2001 GB11list
701Phocaea familyPHO1989AS0.222.4000.22823.4125 Phocaeacatlist
501Juno familyJUN1684BS0.252.6690.23213.343 Juno (adj. Junonian)catlist
502Eunomia familyEUN5670BS0.192.6440.14813.0815 Eunomiacatlist
504Nemesis family
(Liberatrix or Zdeněkhorský family)
NEM1302CC0.052.7500.0885.18128 Nemesis (adj. Nemesian); also named after 58 Concordia (adj. Concordian) and 3827 Zdeněkhorský. Formerly Liberatrix family by Zappalà (1995) and Cellino (2002)catlist
505Adeona familyADE2236BC0.072.6730.16911.71145 Adeonacatlist
506Maria family
(Roma family)
MAR2940BS0.252.5540.10115.02170 Maria; alternatively named after 472 Roma.[8]catlist
507Padua family
(Lydia family)
PAD1087CX0.102.7470.0355.09363 Padua; also known as Lydia family[C] · 110 Lydia · adj. Paduan; Lydiancatlist
508Aeolia familyAEO296CX0.172.7420.1683.49396 Aeoliacatlist
509Chloris familyCLO424CC0.062.7270.2559.23410 Chloris, adj. Chloridiancatlist
510Misa familyMIS702BC0.032.6580.1782.26569 Misa, adj. Misiancatlist
511Brangäne familyBRG195BS0.102.5870.1799.64606 Brangänecatlist
512Dora familyDOR1259CC0.052.7970.1987.83668 Dora, adj. Doriancatlist
513Merxia familyMRX1215CS0.232.7450.1334.85808 Merxia, adj. Merxiancatlist
514Agnia familyAGN2125CS0.182.7830.0663.58847 Agniacatlist
515Astrid familyAST489CC0.082.7880.0480.661128 Astrid, adj. Astridiancatlist
516Gefion family
(Ceres family; Minerva family)
GEF2547CS0.202.7840.1299.011272 Gefion, adj. Gefionian; a-e-i: (2.74 to 2.82; 0.08 to 0.18; 7.4 to 10.5); also known as Ceres family (adj. Cererian) after 1 Ceres; and Minerva (adj. Minervian) family after 93 Minerva (identified interloper)catlist
517König familyKON354BCX0.042.5710.1398.853815 Königcatlist
518Rafita familyRAF1295BS0.252.5470.1737.741644 Rafita, adj. Rafitian (namesake is a suspected interloper; not listed in family); members (1587) and (1658)catlist
519Hoffmeister familyHOF1819CCF0.042.7870.0474.361726 Hoffmeistercatlist
520Iannini familyIAN150BS0.322.6440.26712.194652 Ianninicatlist
521Kazuya familyKAZ44BS0.212.5680.14114.567353 Kazuyacatlist
522Ino familyINO463CS0.242.7430.17213.52173 Inocatlist
523Emilkowalski familyEMI4BS0.202.5990.17817.4214627 Emilkowalski; members: (126761), (224559) and (256124)catlist
524Brugmansia family5243BS2.6200.1792.8016598 Brugmansia; members: (190603) and (218697)catlist
525Schulhof familySHF5BS0.272.6100.16313.302384 Schulhof; members: (81337), (140600), (271044), (286239)catlist
526unnamed family52658CC0.062.7210.17314.35(53546) 2000 BY6list
527Lorre familyLOR2CC0.052.7470.26328.185438 Lorre; other member: (208099)catlist
528Leonidas familyLEO135BCX0.072.6810.1933.812782 Leonidas; identical to the Vibilia family: VIB (and listed as such); (4793)catlist
529Vibilia familyVIB180BC0.062.6550.1913.82144 Vibilia; namesake only listed in family by Zappalà, but not by Nesvorý; identical to the Leonidas family: LEO.catlist
530Phaeo familyPAE146CX0.062.7820.1999.47322 Phaeocatlist
531Mitidika familyMIT653BC0.062.5870.24712.502262 Mitidika (not listed in family itself); members: (404) and (99)catlist
532Henan familyHEN1872BL0.202.6990.0632.802085 Henancatlist
533Hanna familyHNA280CCX0.052.8070.1804.171668 Hannacatlist
534Karma familyKRM124BCX0.052.5770.10610.753811 Karmacatlist
535Witt familyWIT1618CS0.262.7600.0305.792732 Wittcatlist
536Xizang familyXIZ275C0.122.7540.1542.762344 Xizangcatlist
537Watsonia familyWAT99CL0.132.7600.12217.33729 Watsoniacatlist
538Jones family (asteroids)JNS22BT0.052.6260.11012.353152 Jonescatlist
539Aëria familyAER272BX0.172.6490.05611.76369 Aeriacatlist
540Julia family (asteroids)JUL33BS0.192.5520.12416.7089 Juliacatlist
541Postrema familyPOS108CCX0.052.7380.24216.531484 Postremacatlist
801Pallas familyPAL128CB0.162.7710.28133.202 Pallas (adj. Palladian)catlist
802Gallia familyGAL182CS0.172.7710.13225.16148 Galliacatlist
803Hansa familyHNS1094BS0.262.6440.00422.06480 Hansa adj. Hansian; a-e-i: (~2.66; ~0.06; ~22.0°)[9]catlist
804Gersuind familyGER415BS0.152.5890.17517.34686 Gersuindcatlist
805Barcelona familyBAR306BS0.252.6370.25130.83945 Barcelonacatlist
806Tina familyTIN96CX0.342.7930.08220.761222 Tinacatlist
807Brucato familyBRU342BCX0.062.6050.13228.904203 Brucatocatlist
601Hygiea familyHYG4854GCB0.063.1420.1365.0710 Hygieacatlist
602Themis familyTHM4782GC0.073.1340.1521.0824 Themis (adj. Themistian)catlist
603Sylvia familySYL255rimX0.053.4850.0549.7687 Sylvia; family within Cybele groupcatlist
604Meliboea familyMEL444GC0.053.1190.18614.54137 Meliboea, adj. Meliboeancatlist
605Koronis family
(Lacrimosa family)
KOR5949DS0.152.8690.0452.15158 Koronis, also named after 208 Lacrimosacatlist
606Eos familyEOS9789EK0.133.0120.0779.94221 Eoscatlist
607Emma familyEMA76FC0.053.0460.1139.09283 Emmacatlist
608Brasilia familyBRA579DX0.182.8620.12714.98293 Brasilia, adj. Brazilian (namesake is a suspected interloper; not listed in family)catlist
609Veritas familyVER1294GCPD0.073.1740.0669.06490 Veritas, adj. Veritasian; alt: Undina (Undinian) family after 92 Undinacatlist
610Karin familyKAR541DS0.212.8640.0442.10832 Karin. Recently formed family located within the Koronis family.[3]: 8, 18 catlist
611Naëma familyNAE301DC0.082.9400.03611.99845 Naëma, adj. Naëmiancatlist
612Tirela family
(Klumpkea family)
TIR1395GS0.073.1160.19517.061400 Tirela, alternatively named after 1040 Klumpkea (AstDyS)catlist
613Lixiaohua family
(Gantrisch family)
LIX756GCX0.043.1530.20110.063556 Lixiaohua; although member 3330 Gantrisch is both larger and lower numbered (src)catlist
614Telramund family
(Klytaemnestra family)
TEL468ES0.222.9930.0668.819506 Telramund; alternatively named after 179 Klytaemnestra by Masiero and by Milanicatlist
615unnamed family615104DCX0.172.8480.1069.14(18405) 1993 FY12list
616Charis familyCHA808DC0.082.9000.0475.73627 Chariscatlist
617Theobalda familyTHB376GCX0.063.1780.26314.05778 Theobalda, adj. Theobaldian; a-e-i: (3.16 to 3.19; 0.24 to 0.27; 14 to 15)catlist
618Terentia familyTRE79DC0.072.9320.07211.111189 Terentiacatlist
619Lau familyLAU56DS0.272.9290.1956.3010811 Laucatlist
620Beagle familyBGL148GC0.093.1550.1541.34656 Beagle. Recently formed family is located within the Themis family (all members are also listed as Themistians). Includes 7968 Elst–Pizarro.[3]: 7, 8, 18 catlist
621Koronis family (II)K-2246DS0.142.8690.0452.15158 Koronis "second family"catlist
622Terpsichore familyTRP138DC0.052.8540.1828.2381 Terpsichorecatlist
623Fringilla familyFIR134DX0.052.9140.09316.68709 Fringillacatlist
624Durisen familyDUR27DX0.042.9430.18516.195567 Durisencatlist
625Yakovlev familyYAK67DC0.052.8700.2907.895614 Yakovlevcatlist
626San Marcello familySAN144DX0.192.9220.07812.507481 San Marcellocatlist
627unnamed family62738DCX0.052.8680.21916.02(15454) 1998 YB3list
628unnamed family628248DS0.102.8500.0815.12(15477) 1999 CG1list
629unnamed family62958DS0.212.9390.11810.73(36256) 1999 XT17list
630Aegle familyAEG99FCX0.073.0520.19016.4896 Aeglecatlist
631Ursula familyURS1466GCX0.063.1280.09816.21375 Ursulacatlist
632Elfriede familyELF63GC0.053.1890.06115.87618 Elfriedecatlist
633Itha familyITH54DS0.232.8660.15812.27918 Ithacatlist
634Inarradas familyINA38FCX0.073.0500.18414.513438 Inarradascatlist
635Anfimov familyANF58FS0.163.0440.0893.487468 Anfimovcatlist
636Marconia familyMRC34FCX0.053.0630.0972.581332 Marconiacatlist
637unnamed family63764GCX0.053.1090.1803.46(106302) 2000 UJ87list
638Croatia familyCRO93GX0.073.1330.02610.66589 Croatiacatlist
639Imhilde familyIMH43ECX0.052.9830.23714.59926 Imhildecatlist
640Gibbs familyGBS8E3.0040.02310.34331P/Gibbs "P/2012 F5 (Gibbs)". Other members include (20674), (140429), and (177075)
641Juliana familyJLI76ECX0.053.0040.14413.12816 Julianacatlist
901Euphrosyne familyEUP2035GC0.063.1550.20826.5431 Euphrosynecatlist
902Alauda familyALA1294GB0.073.1940.02121.66702 Alaudacatlist
903Ulla familyULA26rimX0.053.5430.05017.96909 Ulla; family within Cybele groupcatlist
904Luthera family
(Kartvelia family)
LUT163GX0.043.2190.12118.771303 Luthera; fam. is also named after 781 Kartveliacatlist
905Armenia familyARM40GC0.053.1170.07018.19780 Armeniacatlist

Other families or dynamical groups

Other asteroid families from miscellaneous sources (not listed in the above table), as well as non-asteroid families include:

FamilyParentCatDescription
Aemilia family159 AemiliaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 62 members.
Alinda family887 AlindacatAlinda group described by projectpluto.com
Amneris family871 AmneriscatSmall family of 22 asteroids identified by Zappalà (1995).[11] Most members have been assigned to the encompassing complex of the Flora family by Nesvorný (2014).[3]
Anius family8060 AniusMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 31 members.
Ashkova family3460 AshkovaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 59 members.
Astraea family5 AstraeacatLarge MBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 6,169 members. Lowest-numbered members: (5), (91), (262), (355), (765) and (1121). Not a listed family by Zappalà (1995).[11] Considered a HCM-artifact by Nesvorný (2014) due to a resonant alignment (z1 = g + s − g6 − s6 = 0).[3]: 19 
Augusta family254 AugustacatSmall family of 23 asteroids identified by Zappalà (1995).[11] Most members have been assigned to the Flora family by Nesvorný (2014).[3]
Ausonia family63 AusoniaSingle member. Unsourced. Member of the Vesta family according to AstDyS-2 and Nesvorný (2014).[3]
Bontekoe family10654 BontekoeMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 13 members.
Brokoff family6769 BrokoffMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 58 members.
Bower family1639 BowerMicro-family with 10 members as per Zappalà (1995). Adj. Bowerian. Alternative name Endymion (Endymionian) family after 342 Endymion.[C] All members: (1639), (3815), (8832), (14306), (15666), (22286), (32637), (85133), (120446) and (145685).[11] This family corresponds in large parts with the König family by Nesvorný (2014).[3]
Cindygraber family7605 CindygraberMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 19 members.
Clematis family1101 ClematiscatMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 17 members. Subset of the large Alauda family as per Nesvorný (2014).[3] All members: (1101), (5360), (22044), (25982), (29963), (32240), (37628), (66174), (71688), (83362), (83790), (97516), (110030), (132961), (147858), (181960) and (223933).
Cybele group65 CybelecatCybele group according to Asteroids, Meteorites, and Comets – by Linda T. Elkins-Tanton and projectpluto.com. Corresponding wiki-category lists a total of 32 members. Not a listed family in HCM by Zappalà (1995), Nesvorný (2014) and AstDyS-2 (Src), where these bodies are predominantly assigned to the background population.[11][3]
Dejanira family157 DejaniracatMicro-family with 5 members as per Zappalà (1995). All members: (157), (2290), (5276), (10779) and (17377).[11] All belong to the background population according to Nesvorný (2014).[3]
Devine family3561 DevineMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 19 members.
Duponta family1338 DupontaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 133 members.
Epeios family2148 EpeiosJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Eumelos family5436 EumelosJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Euryalos family4007 EuryalosJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Faïna family751 FaïnacatCarbonaceous family with 12 identified members as per Zappalà (1995).[11] All members: (751), (2089), (2420), (3637), (3904), (5083), (8087), (10741), (10744), (11497), (12975) and (29086). Predominantly background population with 3 bodies belonging to the stony Maria family per Nesvorný (2014). Not a listed family at AstDyS-2 (Src)
Griqua group1362 GriquacatGriqua group (not a collisional family) described by projectpluto.com. A marginally unstable group of asteroids observed in the 2 :1 resonance with Jupiter.
Hanskya family1118 HanskyaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 116 members.
Haumea familyHaumea (dwarf planet)catThis is a TNO-family. As of 2017, and current categorization, the family consists of 10 members (including parent body).[D]
Helio family895 HelioMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 50 members.
Hestia family46 HestiacatNesvorný moved family (formerly FIN 503) to candidate status, and (46) to background.[3]: 19  Also background according to Milani and Knežević (AstDyS-2).
Higson family3025 HigsonMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 17 members.
Hippasos family17492 HippasosMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 7 members.
Huberta family260 HubertaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 26 members. Nesvorný moved family to candidate status.[3]: 19 
Kalchas family4138 KalchasJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Laodica family507 LaodicacatCategory with 2 members. 507 Laodica and 635 Vundtia are core members of the Eos family according to AstDyS-2 (507; 635) and background asteroid per Nesvorný (507; 635), respectively.[3]
Levin family2076 LevinMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 1534 members.
Liberatrix family125 Liberatrixcat3 listed members. 125 Liberatrix is a background asteroid according to AstDyS-2, and a member of the Nemesis family according to Nesvorný.[3] Background asteroid: 301 Bavaria (both AstDyS-2 and Nesvorný). 9923 Ronaldthiel is a core member of the Agnia family at AstDyS-2.
Makhaon family3063 MakhaonJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Marsili family40134 MarsiliMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 16 members.
Martes family5026 MartescatMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 481 members. Largest asteroids are members of the Erigone family according to Nesvorný (5026; 9879).[3]
Matterania family883 MatteraniaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 169 members.
Mecklenburg family6124 MecklenburgMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 78 members.
Melanthios family12973 MelanthiosJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Menelaus family1647 MenelausJupiter trojan family according Milani (1993).[13] Part of the Menelaus clan according to Roig and Gil-Hutton (2008).[12]
Nele family1547 NeleMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 344 members.
Nocturna family1298 NocturnaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 186 members.
Nohavica family6539 NohavicacatPreviously known as the "1982 QG" family. Second member: (9935) 1986 CP1; both are background asteroids according to AstDyS-2 and Nesvorný.
Podarkes family13062 PodarkesJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Prokne family194 ProkneMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 379 members.
Reginita family1117 ReginitacatClaimed subgroup of the Flora family. Background asteroid according to both AstDyS-2 and Nesvorný.[3]
Sinden family10369 SindenMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 24 members.
Takehiro family8737 TakehiroMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 57 members. Nesvorný moved family to candidate status.[3]: 19 
Telamon family1749 TelamonJupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[12]
Traversa family5651 TraversaMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 56 members.
Univermoscow family6355 UnivermoscowMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 13 members.
Zhvanetskij family5931 ZhvanetskijMBA-family (AstDys) according to Milani and Knežević (2014).[6][10] Total of 23 members.
Legend:
  • C These are families listed as "robustly" identified in Bendjoya and Zappala (2002).
  • D TNOs are not considered asteroids, but are included here for completeness.
  • Candidate families (Nesvorný):[3]: 19  929 Algunde, 1296 Andrée, 1646 Rosseland, 1942 Jablunka, 2007 McCuskey, 2409 Chapman, 4689 Donn, 6246 Komurotoru. (13698) 1998 KF35, 539 Pamina, (300163) 2006 VW139, 3567 Alvema, (7744) 1986 QA1 260 Huberta, 928 Hildrun, 2621 Goto, 1113 Katja, 8737 Takehiro, 46 Hestia, 5 Astraea, 1044 Teutonia, 3110 Wagman, 4945 Ikenozenni, (7744) 1986 QA1, 8905 Bankakuko, (25315) 1999 AZ8, (28804) 2000 HC81.

See also

  • Proper orbital elements
  • Category:Asteroid groups and families

Notes

  1. ^ "close" refers to asteroids inside the 9:2 resonance, "inner" refers to asteroids between the 9:2 and 4:1 resonance. A refers to between 4:1 and 3:1, B is 3:1 to 8:3, C is 8:3 to 5:2, D is 5:2 to 7:3, E is 7:3 to 9:4, F is 9:4 to 11:5, G is 11:5 to 2:1, "outer" refers to asteroids between the 2:1 and 11:6 resonance, and "rim" refers to asteroids beyond the 11:6 resonance.

References

  1. ^ Michael E. Brown, Kristina M. Barkume, Darin Ragozzine & Emily L. Schaller, A collisional family of icy objects in the Kuiper belt, Nature, 446, (March 2007), pp 294-296.
  2. ^ David Nesvorný, Brian L. Enke, William F. Bottke, Daniel D. Durda, Erik Ashaug & Derek C. Richardson Karin cluster formation by asteroid impact, Icarus 183, (2006) pp 296-311.
  3. ^ a b c d e f g h i j k l m n o p q r s t u v Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131. S2CID 119280014.
  4. ^ "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Archived from the original on 2 August 2017. Retrieved 22 July 2017.
  5. ^ This is a joke by Nesvorný et al. In their Table 2 the reference is to the 1995 film, GoldenEye.
  6. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac Milani, Andrea; Cellino, Alberto; Knezevic, Zoran; Novakovic, Bojan; Spoto, Federica; Paolicchi, Paolo (September 2014). "Asteroid families classification: Exploiting very large datasets". Icarus. 239: 46–73. arXiv:1312.7702. Bibcode:2014Icar..239...46M. doi:10.1016/j.icarus.2014.05.039. S2CID 118617163.
  7. ^ a b Carruba, V.; Domingos, R. C.; Nesvorný, D.; Roig, F.; Huaman, M. E.; Souami, D. (August 2013). "A multidomain approach to asteroid families' identification". Monthly Notices of the Royal Astronomical Society. 433 (3): 2075–2096. arXiv:1305.4847. Bibcode:2013MNRAS.433.2075C. doi:10.1093/mnras/stt884.
  8. ^ Masiero, Joseph R.; Mainzer, A. K.; Bauer, J. M.; Grav, T.; Nugent, C. R.; Stevenson, R. (June 2013). "Asteroid Family Identification Using the Hierarchical Clustering Method and WISE/NEOWISE Physical Properties". The Astrophysical Journal. 770 (1): 22. arXiv:1305.1607. Bibcode:2013ApJ...770....7M. doi:10.1088/0004-637X/770/1/7. S2CID 119221614.
  9. ^ The Hansa Family: A New High-Inclination Asteroid Family
  10. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab Knezevic, Zoran; Milani, Andrea; Cellino, Alberto; Novakovic, Bojan; Spoto, Federica; Paolicchi, Paolo (July 2014). "Automated Classification of Asteroids into Families at Work". Complex Planetary Systems. 310: 130–133. Bibcode:2014IAUS..310..130K. doi:10.1017/S1743921314008035.
  11. ^ a b c d e f g Zappalà, V.; Bendjoya, Ph.; Cellino, A.; Farinella, P.; Froeschle, C. (1997). "Asteroid Dynamical Families". NASA Planetary Data System: EAR-A-5-DDR-FAMILY-V4.1. Retrieved 4 March 2020. (PDS main page)
  12. ^ a b c d e f g h i Roig, F.; Ribeiro, A. O.; Gil-Hutton, R. (June 2008). "Taxonomy of asteroid families among the Jupiter Trojans: comparison between spectroscopic data and the Sloan Digital Sky Survey colors". Astronomy and Astrophysics. 483 (3): 911–931. arXiv:0712.0046. Bibcode:2008A&A...483..911R. doi:10.1051/0004-6361:20079177. S2CID 118361725.
  13. ^ Milani, Andrea (October 1993). "The Trojan asteroid belt: Proper elements, stability, chaos and families". Celestial Mechanics and Dynamical Astronomy. 57 (1–2): 59–94. Bibcode:1993CeMDA..57...59M. doi:10.1007/BF00692462. ISSN 0923-2958. S2CID 189850747.

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The orange filaments are the tattered remains of the star and consist mostly of hydrogen. The rapidly spinning neutron star embedded in the center of the nebula is the dynamo powering the nebula's eerie interior bluish glow. The blue light comes from electrons whirling at nearly the speed of light around magnetic field lines from the neutron star. The neutron star, like a lighthouse, ejects twin beams of radiation that appear to pulse 30 times a second due to the neutron star's rotation. A neutron star is the crushed ultra-dense core of the exploded star.

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The newly composed image was assembled from 24 individual Wide Field and Planetary Camera 2 exposures taken in October 1999, January 2000, and December 2000. The colors in the image indicate the different elements that were expelled during the explosion. Blue in the filaments in the outer part of the nebula represents neutral oxygen, green is singly-ionized sulfur, and red indicates doubly-ionized oxygen.
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Asteroid osculating vs proper elements.png
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osculating (Keplerian) zh:orbital elements (left) versus zh:proper orbital elements (right) for numbered zh:asteroids in the zh:main belt. The plots are of zh:inclinations i against eccentricities e.

Clumps in the (right) plot of proper orbital elements indicate the location of asteroid families, while they are almost indistinguishable in the (left) plot of standard Keplerian orbital elements.

This diagram was created by me (Piotr Deuar).

The right plot is a reduced version of zh::Image:Asteroid_proper_elements_i_vs_e.png, an image made using data for 96944 zh:minor planets that was obtained from the AstDys site. This data was dated March 2005, and computed by Z. Knezevic and A. Milani.

The left plot uses Keplerian orbital element data for the same 96944 minor planets taken from the astorb database. This data was dated 27 Dec 2005, and computed by Edward Bowell.
Asteroid proper elements i vs e.png
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