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.
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.
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 asteroid 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).
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.
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.
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.
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).
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.
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.
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
| FIN | Family | Lbl | # of Members[5] | Loc. [note 1] | Taxonomy | mean- albedo | mean a | mean e | mean i | Parent body · Notes | Cat | LoMP |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 001 | Hilda family | HIL | 18 | rim | C | 0.04 | 3.965 | 0.174 | 8.92 | 153 Hilda; adj. Hildian; within the larger dynamical group with the same name. (a–e–i: 3.7–4.2 AU; > 0.07; < 20°) | cat | list |
| 002 | Schubart family | SHU | 531 | rim | C | 0.03 | 3.966 | 0.191 | 2.92 | 1911 Schubart (within the dynamical Hilda group) | cat | list |
| 003 | Hungaria family | H | 1870 | close | E | 0.35 | 1.944 | 0.078 | 20.87 | 434 Hungaria; located within the dynamical group of the same name. (a–e–i: 1.78–2.0 AU; < 0.18; 16°–34°) | cat | list |
| 004 | Hektor family | HEK | 16 | trojan | – | – | 5.204 | 0.054 | 19.02 | 624 Hektor (Jupiter trojan) | cat | list |
| 005 | Eurybates family | ERY | 197 | trojan | CP | 0.06 | 5.204 | 0.044 | 7.42 | 3548 Eurybates (Jupiter trojan) | cat | list |
| 006 | unnamed family | 006 | 15 | trojan | – | 0.06 | 5.204 | 0.049 | 31.75 | 9799 Thronium (Jupiter trojan) | — | list |
| 007 | James Bond family[6] | 007 | 1 | A | ASP | – | 2.474 | 0.129 | 6.32 | 9007 James Bond | — | list |
| 008 | Arkesilaos family | ARK | 37 | trojan | – | – | 5.204 | 0.029 | 8.89 | 20961 Arkesilaos (Jupiter trojan) | cat | list |
| 009 | Ennomos family | ENM | 30 | trojan | – | 0.06 | 5.204 | 0.041 | 26.79 | 4709 Ennomos (Jupiter trojan) | cat | list |
| 010 | unnamed family | 010 | 13 | trojan | – | 0.09 | 5.204 | 0.041 | 24.23 | (247341) 2001 UV209 (Jupiter trojan) | — | list |
| 401 | Vesta family | V | 10612 | A | V | 0.35 | 2.362 | 0.099 | 6.36 | 4 Vesta (adj. Vestian) | cat | list |
| 402 | Flora family (Ariadne family) | FLO | 13786 | A | S | 0.30 | 2.201 | 0.144 | 5.34 | 8 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.[7][8] | cat | list |
| 403 | Baptistina family | BAP | 176 | A | X | 0.16 | 2.264 | 0.149 | 6.00 | 298 Baptistina, merges with the Belgica family (1052) at 100 m/s according to Carruba[8] | cat | list |
| 404 | Massalia family | MAS | 7820 | A | S | 0.22 | 2.409 | 0.162 | 1.42 | 20 Massalia, adj. Massalian, a-e-i: (2.37 to 2.45; 0.12 to 0.21; 0.4 to 2.4) | cat | list |
| 405 | Nysa–Polana complex (Hertha family; Eulalia family) | NYS | 15983 | A | SFC | 0.28 0.06 | 2.423 | 0.174 | 3.04 | 44 Nysa/142 Polana also known as the Hertha family (135 Hertha). Includes the Eulalia family (495 Eulalia) | cat | (44) (142) |
| 406 | Erigone family | ERI | 1776 | A | CX | 0.06 | 2.367 | 0.210 | 4.74 | 163 Erigone, adj. Erigonian. Can be joined with the dynamically different Martes family into a single collisional family (Src). | cat | list |
| 407 | Clarissa family | CLA | 236 | A | X | 0.05 | 2.406 | 0.107 | 3.35 | 302 Clarissa | cat | list |
| 408 | Sulamitis family | SUL | 193 | A | C | 0.04 | 2.463 | 0.091 | 5.04 | 752 Sulamitis | cat | list |
| 409 | Lucienne family | LCI | 142 | A | S | 0.22 | 2.462 | 0.111 | 14.51 | 1892 Lucienne | cat | list |
| 410 | Euterpe family | EUT | 474 | A | S | 0.26 | 2.347 | 0.187 | 0.72 | 27 Euterpe | cat | list |
| 411 | Datura family | DAT | 6 | A | S | 0.21 | 2.235 | 0.156 | 5.21 | 1270 Datura; Recently formed family with members: (60151), (90265), (203370), (215619) and (338309) | cat | list |
| 412 | Lucascavin family | LCA | 3 | A | S | – | 2.281 | 0.127 | 5.20 | 21509 Lucascavin; members: (180255), (209570) | cat | list |
| 413 | Klio family | KLI | 330 | A | C | 0.07 | 2.362 | 0.193 | 9.38 | 84 Klio | cat | list |
| 414 | Chimaera family | CIM | 108 | A | CX | 0.06 | 2.460 | 0.155 | 14.65 | 623 Chimaera | cat | list |
| 415 | Chaldaea family (Salli family) | CHL | 132 | A | C | 0.07 | 2.376 | 0.236 | 11.60 | 313 Chaldaea; alt. named after 1715 Salli by Masiero | cat | list |
| 416 | Svea family | SVE | 48 | A | CX | 0.06 | 2.476 | 0.088 | 16.09 | 329 Svea | cat | list |
| 417 | unnamed family | 417 | 9 | A | – | – | 2.465 | 0.153 | 3.93 | (108138) 2001 GB11 | — | list |
| 701 | Phocaea family | PHO | 1248 | A | S | 0.22 | 2.400 | 0.228 | 23.41 | 25 Phocaea | cat | list |
| 501 | Juno family | JUN | 1693 | B | S | 0.25 | 2.669 | 0.232 | 13.34 | 3 Juno (adj. Junonian) | cat | list |
| 502 | Eunomia family | EUN | 9856 | B | S | 0.19 | 2.644 | 0.148 | 13.08 | 15 Eunomia | cat | list |
| 504 | Nemesis family (Liberatrix or Zdeněkhorský family) | NEM | 1302 | C | C | 0.05 | 2.750 | 0.088 | 5.18 | 128 Nemesis (adj. Nemesian); also named after 58 Concordia (adj. Concordian) and 3827 Zdeněkhorský. Formerly Liberatrix family by Zappalà (1995) and Cellino (2002) | cat | list |
| 505 | Adeona family | ADE | 2070 | B | C | 0.07 | 2.673 | 0.169 | 11.71 | 145 Adeona | cat | list |
| 506 | Maria family (Roma family) | MAR | 2958 | B | S | 0.25 | 2.554 | 0.101 | 15.02 | 170 Maria; alternatively named after 472 Roma.[9] | cat | list |
| 507 | Padua family (Lydia family) | PAD | 1087 | C | X | 0.10 | 2.747 | 0.035 | 5.09 | 363 Padua; also known as Lydia family[C] · 110 Lydia · adj. Paduan; Lydian | cat | list |
| 508 | Aeolia family | AEO | 529 | C | X | 0.17 | 2.742 | 0.168 | 3.49 | 396 Aeolia | cat | list |
| 509 | Chloris family | CLO | 120 | C | C | 0.06 | 2.727 | 0.255 | 9.23 | 410 Chloris, adj. Chloridian | cat | list |
| 510 | Misa family | MIS | 647 | B | C | 0.03 | 2.658 | 0.178 | 2.26 | 569 Misa, adj. Misian | cat | list |
| 511 | Brangäne family | BRG | 325 | B | S | 0.10 | 2.587 | 0.179 | 9.64 | 606 Brangäne | cat | list |
| 512 | Dora family | DOR | 1742 | C | C | 0.05 | 2.797 | 0.198 | 7.83 | 668 Dora, adj. Dorian | cat | list |
| 513 | Merxia family | MRX | 1263 | C | S | 0.23 | 2.745 | 0.133 | 4.85 | 808 Merxia, adj. Merxian | cat | list |
| 514 | Agnia family | AGN | 3336 | C | S | 0.18 | 2.783 | 0.066 | 3.58 | 847 Agnia | cat | list |
| 515 | Astrid family | AST | 548 | C | C | 0.08 | 2.788 | 0.048 | 0.66 | 1128 Astrid, adj. Astridian | cat | list |
| 516 | Gefion family (Ceres family; Minerva family) | GEF | 2428 | C | S | 0.20 | 2.784 | 0.129 | 9.01 | 1272 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) | cat | list |
| 517 | König family | KON | 578 | B | CX | 0.04 | 2.571 | 0.139 | 8.85 | 3815 König | cat | list |
| 518 | Rafita family | RAF | 775 | B | S | 0.25 | 2.547 | 0.173 | 7.74 | 1644 Rafita, adj. Rafitian (namesake is a suspected interloper; not listed in family); members (1587) and (1658) | cat | list |
| 519 | Hoffmeister family | HOF | 2095 | C | CF | 0.04 | 2.787 | 0.047 | 4.36 | 1726 Hoffmeister | cat | list |
| 520 | Iannini family | IAN | 150 | B | S | 0.32 | 2.644 | 0.267 | 12.19 | 4652 Iannini | cat | list |
| 521 | Kazuya family | KAZ | 44 | B | S | 0.21 | 2.568 | 0.141 | 14.56 | 7353 Kazuya | cat | list |
| 522 | Ino family | INO | 463 | C | S | 0.24 | 2.743 | 0.172 | 13.52 | 173 Ino | cat | list |
| 523 | Emilkowalski family | EMI | 4 | B | S | 0.20 | 2.599 | 0.178 | 17.42 | 14627 Emilkowalski; members: (126761), (224559) and (256124) | cat | list |
| 524 | Brugmansia family | 524 | 3 | B | S | – | 2.620 | 0.179 | 2.80 | 16598 Brugmansia; members: (190603) and (218697) | cat | list |
| 525 | Schulhof family | SHF | 5 | B | S | 0.27 | 2.610 | 0.163 | 13.30 | 2384 Schulhof; members: (81337), (140600), (271044), (286239) | cat | list |
| 526 | unnamed family | 526 | 81 | C | C | 0.06 | 2.721 | 0.173 | 14.35 | (53546) 2000 BY6 | — | list |
| 527 | Lorre family | LOR | 2 | C | C | 0.05 | 2.747 | 0.263 | 28.18 | 5438 Lorre; other member: (208099) | cat | list |
| 528 | Leonidas family | LEO | 111 | B | CX | 0.07 | 2.681 | 0.193 | 3.81 | 2782 Leonidas; identical to the Vibilia family: (529/VIB) (and listed as such); (4793) | cat | list |
| 530 | Phaeo family | PAE | 146 | C | X | 0.06 | 2.782 | 0.199 | 9.47 | 322 Phaeo | cat | list |
| 531 | Mitidika family | MIT | 653 | B | C | 0.06 | 2.587 | 0.247 | 12.50 | 2262 Mitidika (not listed in family itself); members: (404) and (99) | cat | list |
| 532 | Henan family | HEN | 1872 | B | L | 0.20 | 2.699 | 0.063 | 2.80 | 2085 Henan | cat | list |
| 533 | Hanna family | HNA | 280 | C | CX | 0.05 | 2.807 | 0.180 | 4.17 | 1668 Hanna | cat | list |
| 534 | Karma family | KRM | 59 | B | CX | 0.05 | 2.577 | 0.106 | 10.75 | 3811 Karma | cat | list |
| 535 | Witt family | WIT | 1618 | C | S | 0.26 | 2.760 | 0.030 | 5.79 | 2732 Witt | cat | list |
| 536 | Xizang family | XIZ | 275 | C | – | 0.12 | 2.754 | 0.154 | 2.76 | 2344 Xizang | cat | list |
| 537 | Watsonia family | WAT | 83 | C | L | 0.13 | 2.760 | 0.122 | 17.33 | 729 Watsonia | cat | list |
| 538 | Jones family (asteroids) | JNS | 22 | B | T | 0.05 | 2.626 | 0.110 | 12.35 | 3152 Jones | cat | list |
| 539 | Aëria family | AER | 272 | B | X | 0.17 | 2.649 | 0.056 | 11.76 | 369 Aeria | cat | list |
| 540 | Julia family (asteroids) | JUL | 33 | B | S | 0.19 | 2.552 | 0.124 | 16.70 | 89 Julia | cat | list |
| 541 | Postrema family | POS | 108 | C | CX | 0.05 | 2.738 | 0.242 | 16.53 | 1484 Postrema | cat | list |
| 801 | Pallas family | PAL | 45 | C | B | 0.16 | 2.771 | 0.281 | 33.20 | 2 Pallas (adj. Palladian) | cat | list |
| 802 | Gallia family | GAL | 137 | C | S | 0.17 | 2.771 | 0.132 | 25.16 | 148 Gallia | cat | list |
| 803 | Hansa family | HNS | 1162 | B | S | 0.26 | 2.644 | 0.004 | 22.06 | 480 Hansa adj. Hansian; a-e-i: (~2.66; ~0.06; ~22.0°)[10] | cat | list |
| 804 | Gersuind family | GER | 415 | B | S | 0.15 | 2.589 | 0.175 | 17.34 | 686 Gersuind | cat | list |
| 805 | Barcelona family | BAR | 346 | B | S | 0.25 | 2.637 | 0.251 | 30.83 | 945 Barcelona | cat | list |
| 806 | Tina family | TIN | 107 | C | X | 0.34 | 2.793 | 0.082 | 20.76 | 1222 Tina | cat | list |
| 807 | Brucato family | BRU | 41 | B | CX | 0.06 | 2.605 | 0.132 | 28.90 | 4203 Brucato | cat | list |
| 601 | Hygiea family | HYG | 3145 | G | CB | 0.06 | 3.142 | 0.136 | 5.07 | 10 Hygiea | cat | list |
| 602 | Themis family | THM | 5612 | G | C | 0.07 | 3.134 | 0.152 | 1.08 | 24 Themis (adj. Themistian) | cat | list |
| 603 | Sylvia family | SYL | 191 | rim | X | 0.05 | 3.485 | 0.054 | 9.76 | 87 Sylvia; family within Cybele group | cat | list |
| 604 | Meliboea family | MEL | 444 | G | C | 0.05 | 3.119 | 0.186 | 14.54 | 137 Meliboea, adj. Meliboean | cat | list |
| 605 | Koronis family (Lacrimosa family) | KOR | 7390 | D | S | 0.15 | 2.869 | 0.045 | 2.15 | 158 Koronis, also named after 208 Lacrimosa | cat | list |
| 606 | Eos family | EOS | 16038 | E | K | 0.13 | 3.012 | 0.077 | 9.94 | 221 Eos | cat | list |
| 607 | Emma family | EMA | 577 | F | C | 0.05 | 3.046 | 0.113 | 9.09 | 283 Emma | cat | list |
| 608 | Brasilia family | BRA | 845 | D | X | 0.18 | 2.862 | 0.127 | 14.98 | 293 Brasilia, adj. Brazilian (namesake is a suspected interloper; not listed in family) | cat | list |
| 609 | Veritas family | VER | 2139 | G | CPD | 0.07 | 3.174 | 0.066 | 9.06 | 490 Veritas, adj. Veritasian; alt: Undina (Undinian) family after 92 Undina | cat | list |
| 610 | Karin family | KAR | 541 | D | S | 0.21 | 2.864 | 0.044 | 2.10 | 832 Karin. Recently formed family located within the Koronis family.[3]: 8, 18 | cat | list |
| 611 | Naëma family | NAE | 375 | D | C | 0.08 | 2.940 | 0.036 | 11.99 | 845 Naëma, adj. Naëmian | cat | list |
| 612 | Tirela family (Klumpkea family) | TIR | 1815 | G | S | 0.07 | 3.116 | 0.195 | 17.06 | 1400 Tirela, alternatively named after 1040 Klumpkea (AstDyS) | cat | list |
| 613 | Lixiaohua family (Gantrisch family) | LIX | 1241 | G | CX | 0.04 | 3.153 | 0.201 | 10.06 | 3556 Lixiaohua; although member 3330 Gantrisch is both larger and lower numbered (src) | cat | list |
| 614 | Telramund family (Klytaemnestra family) | TEL | 513 | E | S | 0.22 | 2.993 | 0.066 | 8.81 | 9506 Telramund; alternatively named after 179 Klytaemnestra by Masiero and by Milani | cat | list |
| 615 | unnamed family | 615 | 159 | D | CX | 0.17 | 2.848 | 0.106 | 9.14 | (18405) 1993 FY12 | — | list |
| 616 | Charis family | CHA | 808 | D | C | 0.08 | 2.900 | 0.047 | 5.73 | 627 Charis | cat | list |
| 617 | Theobalda family | THB | 574 | G | CX | 0.06 | 3.178 | 0.263 | 14.05 | 778 Theobalda, adj. Theobaldian; a-e-i: (3.16 to 3.19; 0.24 to 0.27; 14 to 15) | cat | list |
| 618 | Terentia family | TRE | 80 | D | C | 0.07 | 2.932 | 0.072 | 11.11 | 1189 Terentia | cat | list |
| 619 | Lau family | LAU | 56 | D | S | 0.27 | 2.929 | 0.195 | 6.30 | 10811 Lau | cat | list |
| 620 | Beagle family | BGL | 148 | G | C | 0.09 | 3.155 | 0.154 | 1.34 | 656 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 | cat | list |
| 621 | Koronis family (II) | K-2 | 246 | D | S | 0.14 | 2.869 | 0.045 | 2.15 | 158 Koronis "second family" | cat | list |
| 622 | Terpsichore family | TRP | 138 | D | C | 0.05 | 2.854 | 0.182 | 8.23 | 81 Terpsichore | cat | list |
| 623 | Fringilla family | FIR | 134 | D | X | 0.05 | 2.914 | 0.093 | 16.68 | 709 Fringilla | cat | list |
| 624 | Durisen family | DUR | 27 | D | X | 0.04 | 2.943 | 0.185 | 16.19 | 5567 Durisen | cat | list |
| 625 | Yakovlev family | YAK | 67 | D | C | 0.05 | 2.870 | 0.290 | 7.89 | 5614 Yakovlev | cat | list |
| 626 | San Marcello family | SAN | 144 | D | X | 0.19 | 2.922 | 0.078 | 12.50 | 7481 San Marcello | cat | list |
| 627 | unnamed family | 627 | 38 | D | CX | 0.05 | 2.868 | 0.219 | 16.02 | (15454) 1998 YB3 | — | list |
| 628 | unnamed family | 628 | 248 | D | S | 0.10 | 2.850 | 0.081 | 5.12 | (15477) 1999 CG1 | — | list |
| 629 | unnamed family | 629 | 58 | D | S | 0.21 | 2.939 | 0.118 | 10.73 | (36256) 1999 XT17 | — | list |
| 630 | Aegle family | AEG | 120 | F | CX | 0.07 | 3.052 | 0.190 | 16.48 | 96 Aegle | cat | list |
| 631 | Ursula family | URS | 731 | G | CX | 0.06 | 3.128 | 0.098 | 16.21 | 375 Ursula | cat | list |
| 632 | Elfriede family | ELF | 97 | G | C | 0.05 | 3.189 | 0.061 | 15.87 | 618 Elfriede | cat | list |
| 633 | Itha family | ITH | 54 | D | S | 0.23 | 2.866 | 0.158 | 12.27 | 918 Itha | cat | list |
| 634 | Inarradas family | INA | 43 | F | CX | 0.07 | 3.050 | 0.184 | 14.51 | 3438 Inarradas | cat | list |
| 635 | Anfimov family | ANF | 49 | F | S | 0.16 | 3.044 | 0.089 | 3.48 | 7468 Anfimov | cat | list |
| 636 | Marconia family | MRC | 34 | F | CX | 0.05 | 3.063 | 0.097 | 2.58 | 1332 Marconia | cat | list |
| 637 | unnamed family | 637 | 64 | G | CX | 0.05 | 3.109 | 0.180 | 3.46 | (106302) 2000 UJ87 | — | list |
| 638 | Croatia family | CRO | 93 | G | X | 0.07 | 3.133 | 0.026 | 10.66 | 589 Croatia | cat | list |
| 639 | Imhilde family | IMH | 43 | E | CX | 0.05 | 2.983 | 0.237 | 14.59 | 926 Imhilde | cat | list |
| 640 | Gibbs family | GBS | 8 | E | – | – | 3.004 | 0.023 | 10.34 | 331P/Gibbs "P/2012 F5 (Gibbs)". Other members include (20674), (140429), and (177075) | — | — |
| 641 | Juliana family | JLI | 76 | E | CX | 0.05 | 3.004 | 0.144 | 13.12 | 816 Juliana | cat | list |
| 901 | Euphrosyne family | EUP | 1385 | G | C | 0.06 | 3.155 | 0.208 | 26.54 | 31 Euphrosyne | cat | list |
| 902 | Alauda family | ALA | 1294 | G | B | 0.07 | 3.194 | 0.021 | 21.66 | 702 Alauda | cat | list |
| 903 | Ulla family | ULA | 37 | rim | X | 0.05 | 3.543 | 0.050 | 17.96 | 909 Ulla; family within Cybele group | cat | list |
| 904 | Luthera family (Kartvelia family) | LUT | 232 | G | X | 0.04 | 3.219 | 0.121 | 18.77 | 1303 Luthera; fam. is also named after 781 Kartvelia | cat | list |
| 905 | Armenia family | ARM | 67 | G | C | 0.05 | 3.117 | 0.070 | 18.19 | 780 Armenia | cat | list |
Other asteroid families from miscellaneous sources (not listed in the above table), as well as non-asteroid families include:
| Family | Parent | Cat | Description | |
|---|---|---|---|---|
| Aemilia family | 159 Aemilia | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 62 members. | |
| Alinda family | 887 Alinda | cat | Alinda group described by projectpluto.com | |
| Amneris family | 871 Amneris | cat | Small family of 22 asteroids identified by Zappalà (1995).[12] Most members have been assigned to the encompassing complex of the Flora family by Nesvorný (2014).[3] | |
| Anius family | 8060 Anius | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 31 members. | |
| Ashkova family | 3460 Ashkova | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 59 members. | |
| Astraea family | 5 Astraea | cat | Large MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 6,169 members. Lowest-numbered members: (5), (91), (262), (355), (765) and (1121). Not a listed family by Zappalà (1995).[12] Considered a HCM-artifact by Nesvorný (2014) due to a resonant alignment (z1 = g + s − g6 − s6 = 0).[3]: 19 | |
| Augusta family | 254 Augusta | cat | Small family of 23 asteroids identified by Zappalà (1995).[12] Most members have been assigned to the Flora family by Nesvorný (2014).[3] | |
| Ausonia family | 63 Ausonia | — | Single member. Unsourced. Member of the Vesta family according to AstDyS-2 and Nesvorný (2014).[3] | |
| Bontekoe family | 10654 Bontekoe | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 13 members. | |
| Brokoff family | 6769 Brokoff | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 58 members. | |
| Bower family | 1639 Bower | — | Micro-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).[12] This family corresponds in large parts with the König family by Nesvorný (2014).[3] | |
| Cindygraber family | 7605 Cindygraber | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 19 members. | |
| Clematis family | 1101 Clematis | cat | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] 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 group | 65 Cybele | cat | Cybele 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.[12][3] | |
| Dejanira family | 157 Dejanira | cat | Micro-family with 5 members as per Zappalà (1995). All members: (157), (2290), (5276), (10779) and (17377).[12] All belong to the background population according to Nesvorný (2014).[3] | |
| Devine family | 3561 Devine | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 19 members. | |
| Duponta family | 1338 Duponta | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 133 members. | |
| Epeios family | 2148 Epeios | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Eumelos family | 5436 Eumelos | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Euryalos family | 4007 Euryalos | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Faïna family | 751 Faïna | cat | Carbonaceous family with 12 identified members as per Zappalà (1995).[12] 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 group | 1362 Griqua | cat | Griqua group (not a collisional family) described by projectpluto.com. A marginally unstable group of asteroids observed in the 2 :1 resonance with Jupiter. | |
| Hanskya family | 1118 Hanskya | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 116 members. | |
| Haumea family | Haumea (dwarf planet) | cat | This is a TNO-family. As of 2017, and current categorization, the family consists of 10 members (including parent body).[D] | |
| Helio family | 895 Helio | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 50 members. | |
| Hestia family | 46 Hestia | cat | Nesvorný moved family (formerly FIN 503) to candidate status, and (46) to background.[3]: 19 Also background according to Milani and Knežević (AstDyS-2). | |
| Higson family | 3025 Higson | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 17 members. | |
| Hippasos family | 17492 Hippasos | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 7 members. | |
| Huberta family | 260 Huberta | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 26 members. Nesvorný moved family to candidate status.[3]: 19 | |
| Kalchas family | 4138 Kalchas | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Laodica family | 507 Laodica | cat | Category 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 family | 2076 Levin | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 1534 members. | |
| Liberatrix family | 125 Liberatrix | cat | 3 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 family | 3063 Makhaon | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Marsili family | 40134 Marsili | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 16 members. | |
| Martes family | 5026 Martes | cat | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 481 members. Largest asteroids are members of the Erigone family according to Nesvorný (5026; 9879).[3] | |
| Matterania family | 883 Matterania | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 169 members. | |
| Mecklenburg family | 6124 Mecklenburg | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 78 members. | |
| Melanthios family | 12973 Melanthios | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Menelaus family | 1647 Menelaus | — | Jupiter trojan family according Milani (1993).[14] Part of the Menelaus clan according to Roig and Gil-Hutton (2008).[13] | |
| Nele family | 1547 Nele | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 344 members. | |
| Nocturna family | 1298 Nocturna | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 186 members. | |
| Nohavica family | 6539 Nohavica | cat | Previously known as the "1982 QG" family. Second member: (9935) 1986 CP1; both are background asteroids according to AstDyS-2 and Nesvorný. | |
| Podarkes family | 13062 Podarkes | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Prokne family | 194 Prokne | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 379 members. | |
| Reginita family | 1117 Reginita | cat | Claimed subgroup of the Flora family. Background asteroid according to both AstDyS-2 and Nesvorný.[3] | |
| Sinden family | 10369 Sinden | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 24 members. | |
| Takehiro family | 8737 Takehiro | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 57 members. Nesvorný moved family to candidate status.[3]: 19 | |
| Telamon family | 1749 Telamon | — | Jupiter trojan family according to Roig and Gil-Hutton (2008). Part of the Menelaus clan.[13] | |
| Traversa family | 5651 Traversa | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 56 members. | |
| Univermoscow family | 6355 Univermoscow | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 13 members. | |
| Zhvanetskij family | 5931 Zhvanetskij | — | MBA-family (AstDys) according to Milani and Knežević (2014).[7][11] Total of 23 members. | |
Legend:
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