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List of multiplanetary systems
List of multiplanetary systems
from Wikipedia
Number of extrasolar planet discoveries per year through 2023. Colors indicate method of detection.

From the total of 4,490 stars known to have exoplanets (as of October 2, 2025), there are a total of 1,013 known multiplanetary systems,[1] or stars with at least two confirmed planets, beyond the Solar System. This list includes systems with at least three confirmed planets or two confirmed planets where additional candidates have been proposed. The stars with the most confirmed planets are the Sun (the Solar System's star) and Kepler-90, with 8 confirmed planets each, followed by TRAPPIST-1 with 7 planets.

The 1,013 multiplanetary systems are listed below according to the star's distance from Earth. Proxima Centauri, the closest star to the Solar System, has at least two planets (the confirmed b, d and the disputed c[2]). The nearest system with four or more confirmed planets is Barnard Star, with four known.[3] The farthest confirmed system with two or more planets is OGLE-2012-BLG-0026L, at 13,300 light-years (4,100 pc) away.[4]

The table below contains information about the coordinates, spectral and physical properties, and the number of confirmed (unconfirmed) planets for systems with at least 2 planets and 1 not confirmed. The two most important stellar properties are mass and metallicity because they determine how these planetary systems form. Systems with higher mass and metallicity tend to have more planets and more massive planets. However, although low metallicity stars tend to have fewer massive planets, particularly hot-Jupiters, they also tend to have a larger number of close-in planets, orbiting at less than 1 AU.[5]

Multiplanetary systems

[edit]
|
Color indicates number of planets
2 (x) 3 4 5 6 7 8 9
Star
Constellation
Right
ascension

Declination
Apparent
magnitude

Distance (ly)
Spectral
type

Mass
(M)
Temperature (K)
Age
(Gyr)
Confirmed
(unconfirmed)
planets
Notes
Sun Aries 2h 2m 54s - −26.74 0.000016 G2V 1 5778 4.572 8 (2) Has 8 confirmed planets, and 2 unconfirmed ones. Only known system to have life.
Proxima Centauri Centaurus 14h 29m 42.94853s −62° 40′ 46.1631″ 10.43 to 11.11[6] 4.244 M5.5Ve[7] 0.122 3042 4.85 2 (1) Closest star to the Sun and closest star to the Sun with a multiplanetary system. Planet b is potentially habitable.[8][9]
Barnard's Star Ophiuchus 17h 57m 48.4985s +04° 41′ 36.1139″ 9.511 5.96 M4.0V[10] 0.162 3195 10 4 (0) Closest single star to the Sun with a confirmed multiplanetary system.[3]
Lalande 21185 Ursa Major 11h 03m 20.1940s +35° 58′ 11.5682″ 7.520[11] 8.3044±0.0007 M2V 0.39 3601±51 8.047 2 (1) Brightest red dwarf star in the northern celestial hemisphere.[12][13]
Lacaille 9352 Piscis Austrinus 23h 05m 52.04s −35° 51′ 11.05″ 7.34 10.721 M0.5V 0.486 3688±86 4.57 2 (1) The unconfirmed planet d is potentially habitable.[14]
Luyten's Star Canis Minor 07h 27m 24.4991s 05° 13′ 32.827″ 9.872 11.20 M3.5V 0.26 3150 unknown 2 (2) Stellar activity level and rotational rate suggest an age higher than 8 billion years.[15] Planet b is potentially habitable.[16]
YZ Ceti Cetus 01h 12m 30.64s −16° 59′ 56.3″ 12.07 11.74 M4.5V 0.13 3056 4 3 (1) Flare star.[17]
Gliese 1061 Horologium 03h 35m 59.69s −44° 30′ 45.3″ 13.03 12.04 M5.5V 0.113 2953 unknown 3 Planets c and d are potentially habitable.[18]
Teegarden's Star Aries 02h 53m 00.89s +16° 52′ 53″ 15.13 12.497 M7V 0.097 3034 8 3 Teegarden's Star b and Teegarden's Star c are likely Earth-mass planets that orbit in the habitable zone.[19]
Wolf 1061 Ophiuchus 16h 30m 18.0584s −12° 39′ 45.325″ 10.07 14.050 ± 0.002 M3.5V 0.294 3342 unknown 3 Planet c is potentially habitable.[20][21][22]
Gliese 876 Aquarius 22h 53m 16.73s −14° 15′ 49.3″ 10.17 15.25 M4V 0.334 3348 4.893 4 Planet b is a gas giant which orbits in the habitable zone.[23]
82 G. Eridani Eridanus 03h 19m 55.65s −43° 04′ 11.2″ 4.254 19.71 G8V 0.7 5401 5.76 3 (3) This star also has a dust disk[24] with a semi-major axis at approximately 19 AU.[25]
Gliese 581 Libra 15h 19m 26.83s −07° 43′ 20.2″ 10.56 20.56 M3V 0.311 3484 4.326 3 (1) The disputed planet d is potentially habitable.[26]
Gliese 667 C Scorpius 17h 18m 57.16s −34° 59′ 23.14″ 10.20 21 M1.5V 0.31 3700 2 2 (1) Triple star system - all exoplanets orbit around Star C. Planet c is potentially habitable, There were thought to be up to 5 more planets orbiting the star, Gliese 667 Cd, Ce, Cf, Cg, and Ch but most of them were false positives except for planet d which remains uncomfirmed .[27][28][29]
HD 219134 Cassiopeia 23h 13m 14.74s 57° 10′ 03.5″ 5.57 21 K3Vvar 0.794 4699 12.66 6 Closest star to the Sun with exactly six[30] exoplanets, and closest K-type main sequence star to the Sun with a multiplanetary system. One of the oldest stars with a multiplanetary system, although it is still more metal-rich than the Sun. None of the known planets is in the habitable zone.[31]
61 Virginis Virgo 13h 18m 24.31s −18° 18′ 40.3″ 4.74 28 G5V 0.954 5531 8.96 2 (1) Planet d remains unconfirmed,[32] and a 2021 study found that it was likely a false positive.[33] 61 Virginis also has a debris disk.
Gliese 433 Hydra 11h 35m 26.9485s −25° 10′ 08.9″ 9.79 29.8±0.1 M1.5V 0.48 3550±100 unknown 3 An infrared excess around this star suggests a circumstellar disk.[34]
Gliese 357 Hydra 09h 36m 01.6373s −21° 39′ 38.878″ 10.906 30.776 M2.5V 0.362 3488 unknown 3 Planet d is a potentially habitable Super-Earth.[35][36][37][38]
L 98-59 Volans 08h 18m 07.62s −68° 18′ 46.8″ 11.69 34.6 M3V 0.312 3412 unknown 5 (1) The unconfirmed planet g orbits in closer than b.[39]
Gliese 414 A Ursa Major 11h 11m 05.88s 30° 26′ 42.61″ 8.31 38.76 K7V 0.65 4120 12.4 2 (0) [40][41]
Gliese 806 Cygnus 20h 45m 04.099s +44° 29′ 56.6″ 10.79 39.3 M1.5V 0.423 3586 3 2 (1) -
TRAPPIST-1 Aquarius 23h 06m 29.283s −05° 02′ 28.59″ 18.80 39.5 M8V 0.089 2550 7.6 7 (1) Planets d, e, f and g are potentially habitable. Only star known with exactly seven confirmed planets. All seven confirmed terrestrial planets lie within only 0.07 AU of the star.
55 Cancri B Cancer 08h 52m 40.8627s +28° 19′ 58.821″ 13.15 40.95 M4.5V 0.264 3320 8.6 2 Both planets are super-earths. At least four others orbit around star A, of which two are unconfirmed. First star system known where more than one star has an individual multiplanetary system.
55 Cancri A Cancer 08h 52m 35.8111s +28° 19′ 50.96″ 5.95 41.05 K0IV-V 0.905 5172 8.6 4 (2) Planets 55 Cancri Ad and 55 Cancri Ag are unconfirmed. All but 55 Cancri Ae (which is a super-earth) are giant planets. Two others orbit around star B. First star system known where more than one star has an individual planetary system.
Gliese 180 Eridanus 04h 53m 49.9798s −17° 46′ 24.294″ 10.894 40.3 M2V[42] or M3V[43] 0.39 3562 unknown 3 The habitability of planets b and c is disputed.[44][45]
HD 69830 Puppis 08h 18m 23.95s −12° 37′ 55.8″ 5.95 41 K0V 0.856 5385 7.446 3 A debris disk exterior to the three exoplanets was detected by the Spitzer Space Telescope in 2005.[46]
HD 40307 Pictor 05h 54m 04.24s −60° 01′ 24.5″ 7.17 42 K2.5V 0.752 4977 1.198 4 (2) The existence of planets e and g are disputed.[47] If confirmed, planet g is potentially habitable.[48]
Upsilon Andromedae Andromeda 01h 36m 47.84s +41° 24′ 19.7″ 4.09 44 F8V 1.27 6107 3.781 3 (1) Nearest F-type main sequence star with a multiplanetary system. Second-brightest star in the night sky with a multiplanetary system after 7 Canis Majoris. All exoplanets orbit around star A in the binary system. The existence Of Planet e is disputed.
47 Ursae Majoris Ursa Major 10h 59m 27.97s +40° 25′ 48.9″ 5.10 46 G0V 1.029 5892 7.434 3 Planet Taphao Thong was discovered in 1996 and was one of the first exoplanets to be discovered.[49] The planet was the first long-period extrasolar planet discovered. The other planets were discovered later.[50]
Nu2 Lupi Lupus 15h 21m 49.57s −48° 19′ 01.1″ 5.65 47 G2V 0.906 5664 10.36 3 One of the oldest stars in the solar neighbourhood.[51][52][53]
LHS 1140 Cetus 00h 44m 59.31s −15° 16′ 16.7″ 14.18 48.9 M4.5V[54] 0.179 3216±39 5 2 (1) Planet b is a potentially habitable Super-Earth.[55]
Gliese 163 Dorado 04h 09m 16s −53° 22′ 25″ 11.8 49 M3.5V 0.4 unknown 3 5 Planet c is possibly a potentially habitable Super-Earth but is probably too hot or massive.[56][57]
Mu Arae Ara 17h 44m 08.70s −51° 50′ 02.6″ 5.15 51 G3IV-V 1.077 5704 6.413 4 Planet Quijote orbits in the circumstellar habitable zone. However, it is a gas giant, so it itself is uninhabitable although a large moon orbiting around it may be habitable.
GJ 3929 Corona Borealis 15h 58m 18.8s 35° 24′ 24.3″ 12.67 51.58 M3.5V 0.313 3384 unknown 2 (0) [58][59]
Gliese 676 A Ara 17h 30m 11.2042s −51° 38′ 13.116″ 9.59 53 M0V 0.71 unknown unknown 4 Held the record for widest range of masses in a planetary system in 2012.[60]
HD 7924 Cassiopeia 01h 21m 59.12s +76° 42′ 37.0″ 7.19 55 K0V 0.832 5177 unknown 3 These planets may be potentially habitable Super-Earths.[61]
Pi Mensae Mensa 05h 37m 09.8851s −80° 28′ 08.8313″ 5.65 59.62±0.07 G0V 1.11 6013 3.4 3 Outer planet is likely a brown dwarf.[62]
Gliese 3293 Eridanus 04h 28m 35.72s −25° 10′ 08.9″ 11.96 59 M2.5V 0.42 3466±49 unknown 4 Planets b and d orbit in the habitable zone.[16]
LHS 1678 Caelum 04h 32m 43s −39° 47′ 21″ 12 64.8 M2V 0.345 3490 unknown 3 (0) [63]
HD 104067 Corvus 11h 59m 10.0s −20° 21′ 13.6″ 7.92 66.3 K3V 0.82 4942 4.8 2 (1) The innermost planet, which is unconfirmed, might suffer from significant tidal heating.[64]
HD 142 Phoenix 00h 06m 19.0s −49° 04′ 30″ 5.70 67 G1 IV 1.1 6180 5.93 3 -
HD 215152 Aquarius 22h 43m 21s −06° 24′ 03″ 8.13 70 G8IV 1.019 5646 7.32 4 A debris disk candidate as it has an infrared excess.[65]
HD 164922 Hercules 18h 02m 30.86s +26° 18′ 46.8″ 7.01 72 G9V[66] 0.874 5293 13.4 4 Oldest star with a multiplanetary system. Despite its age, it is more metal-rich than the Sun.[66]
HD 63433 Gemini 07h 49m 55.0s +27° 21′ 47.4″ 6.92 73 G5V 0.99 5640 0.4 3
HIP 57274 Ursa Major 11h 44m 41s +30° 57′ 33″ 8.96 85 K5V 0.73 4640 7.87 3 -
HD 39194 Mensa 05h 44m 32s −70° 08′ 37″ 8.08 86.2 K0V unknown 5205 unknown 3 The planets have eccentric orbits.[67]
LP 791-18 Crater 11h 02m 45.95s −16° 24′ 22.3″ 16.9 86.9 M6V/M7V 0.139 2960 0.5 3
HD 181433 Pavo 19h 25m 09.57s −66° 28′ 07.7″ 8.38 87 K5V 0.777 4962 8.974 3 -
HD 134606 Apus 15h 15m 15s −70° 31′ 11″ 6.85 87 G6IV unknown unknown unknown 5 The planets have moderately eccentric orbits.[68]
HD 158259 Draco 17h 25m 24.0s +52° 47′ 26″ 6.46 89 G0 1.08 unknown unknown 5 (1) A G-type star slightly more massive than the Sun.[69] Planet g remains unconfirmed.[69]
HD 82943 Hydra 09h 34m 50.74s −12° 07′ 46.4″ 6.54 90 F9V Fe+0.5[70] 1.175 5874 3.08 3 Planets b and c are in a 2:1 orbital resonance.[71] Planet b orbits in the habitable zone, but it and planet c are massive enough to be brown dwarfs. HD 82943 has an unusual lithium-6 abundance.[72]
Gliese 3138 Cetus 02h 09m 10.90s −16° 20′ 22.53″ 10.877 92.9 0.681 3717±49 unknown 3
GJ 9827 Pisces 23h 27m 04.84s −01° 17′ 10.59″ 10.10 96.8±0.2 K6V 0.593 4294±52 unknown 3 Also known as K2-135. Planet b is extremely dense, with at least half of its mass being iron.[73]
Iota Draconis Draco 15h 24m 55.8s +58° 57′ 57.3″ 3.290 101.2 unknown 1.56 4504 2.49 2 Iota Draconis is already in its red giant phase, both planets have very eccentric orbits.
K2-239 Sextans 10h 42m 22.63s +04° 26′ 28.86″ 14.5 101.5 M3V 0.4 3420 unknown 3
TOI-700 Dorado 06h 28m 22.97s −65° 34′ 43.01″ 13.10 101.61 M2V 0.416 3480 1.5 4 Planets d and e are potentially habitable.[74][75][76]
HD 17926 Fornax 02h 51m 56.16s −30° 48′ 53.2″ 6.38 105 F6V 1.145 6201 unknown 3 The star forms a binary with a red dwarf.[77]
HD 37124 Taurus 05h 37m 02.49s +20° 43′ 50.8″ 7.68 110 G4V 0.83 5606 3.327 3 Planet c orbits at the outer edge of the habitable zone.[78]
HD 20781 Fornax 03h 20m 03s −28° 47′ 02″ 8.44 115 G9.5V 0.7 5256±29 unknown 4 Located in binary star system.[79][80]
Kepler-444 Lyra 19h 19m 01s 41° 38′ 05″ 9.0 117 K0V 0.758 5040 11.23 5 Nearest multiplanetary system where the planets were discovered by the Kepler space telescope.
HD 141399 Boötes 15h 46m 54.0s +46° 59′ 11″ 7.2 118 K0V 1.07 5600 unknown 4 Planet c orbits in the habitable zone.[81]
Kepler-42 Cygnus 19h 28m 53s +44° 37′ 10″ 16.12 126 M5V[82] 0.13 3068 unknown 3 -
HD 31527 Lepus 04h 55m 38s −23° 14′ 31″ 7.48 126 G0V unknown unknown unknown 3 -
HD 10180 Hydrus 01h 37m 53.58s −60° 30′ 41.5″ 7.33 127 G1V 1.055 5911 4.335 6 (3) Has 6 confirmed planets orbiting around it, Evidence for 3 more planets in the system exist, If these worlds are confirmed, this system would be the largest planetary system found. [83]
HD 23472 Reticulum 03h 41m 50.3988s −62° 46′ 01.4772″ 9.72 127.48 K3.5V 0.67 4684±99 unknown 5
HR 8799 Pegasus 23h 07m 28.72s +21° 08′ 03.3″ 5.96 129 A5V 1.472 7429 0.064 4 (1) Only A-type main sequence star with a known multiplanetary system, and hottest and most massive single main sequence star with a multiplanetary system. All four planets are massive super-Jupiters.
HD 27894 Reticulum 04h 20m 47.05s −59° 24′ 39.0″ 9.42 138 K2V 0.8 4875 3.9 3 -
HD 93385 Vela 10h 46m 15.1160s −41° 27′ 51.7261″ 7.486 141.6 G2V 1.07 5823 4.13 3
K2-3 Leo 11h 29m 20.3918s −01° 27′ 17.280″ 12.168 143.9±0.4 M0V 0.601 3835±70 1 3 The outermost planet orbits in the habitable zone.[84]
HD 34445 Orion 05h 17m 41.0s +07° 21′ 12″ 7.31 152 G0V 1.07 5836 8.5 1 (5) Some planets were not detected or inferred to be false positives in a later study.[33]
HD 204313 Capricornus 21h 28m 12.21s –21° 43′ 34.5″ 7.99 154 G5V 1.045 5767 3.38 3 -
HD 3167 Pisces 00h 34m 57.5s +04° 22′ 53″ 8.97 154.4 K0V 0.852 5300 10.2 4 -
HIP 34269 Puppis 07h 06m 13.98s −47° 35′ 13.87″ 10.59 154.81 0.74 4440±100 unknown 4
HD 133131 Libra 15h 03m 35.80651s −27° 50′ 27.5520″ 8.4 168 G2V+G2V[85] 0.95 5799±19 6 3 2 planets around primary, and 1 planet around secondary star.[85]
K2-136 Taurus 04h 29m 38.99s +22° 52′ 57.80″ 11.2 173 K5V 0.71 4364±70 0.7 3
HIP 14810 Aries 03h 11m 14.23s +21° 05′ 50.5″ 8.51 174 G5V 0.989 5485 5.271 3 -
HD 191939 Draco 20h 08m 05.75s +66° 51′ 2.1″ 8.971 175 G9V 0.81 5348 8.7 6 [86]
HD 125612 Virgo 14h 20m 53.51s −17° 28′ 53.5″ 8.33 177 G3V 1.099 5897 2.15 3 -
HD 184010 Vulpecula 19h 31m 22.0s +26° 37′ 02″ 5.9 200 KOIII-IV 1.35 4971 2.76 3 -
HD 109271 Virgo 12h 33m 36.0s −11° 37′ 19″ 8.05 202 G5 1.047 5783 7.3 2 (1) -
HD 38677 Orion 05h 47m 06.0s −10° 37′ 49″″ 8.0 202 F8V 1.21 6196.0 2.01 4 -
TOI-178 Sculptor 00h 29m 12.30s 30° 27′ 13.46″ 11.95 205.16 K7V[87] 0.65 4316±70 7.1 6 The planets are in an orbital resonance.[87]
HD 108236 Centaurus 12h 26m 17.89s −51° 21′ 46.21″ 9.24 211 G3V 0.97 5730 5.8 5 -
Kepler-37 Lyra 18h 58m 23.1s 44° 31′ 05″ 9.77 215 G8V 0.803 5417 6 3 (1) The existence of Kepler-37e is dubious.[88]
K2-72 Aquarius 22h 18m 29.2548s −09° 36′ 44.3824″ 15.04 217 M2V 0.27 3497 unknown 4 2 planets in habitable zone
Kepler-138 Lyra 19h 21m 32.0s +43° 17′ 35″ 13.5 218.5 M1V 0.57 3871 unknown 3 (1)
K2-233 Libra 15h 21m 55.2s −20° 13′ 54″ 10.0 221 K3 0.8 4950 0.36 3
TOI-1260 Ursa Major 10h 28m 35.03s +65° 51′ 16.38″ 11.973 239.5 0.66 4227±85 6.7 3
LP 358-499 Taurus 04h 40m 35.64s +25° 00′ 36.05″ 13.996 245.3 0.46 3655±80 unknown 4 Also known as K2-133
K2-266 Sextans 10h 31m 44.5s +00° 56′ 15″ 252 K 0.69 4285 8.4 4 (2)
K2-155 Taurus 04h 21m 52.5s +21° 21′ 13″ 12.8 267 K7 0.65 4258 unknown 3
K2-384 Cetus 01h 21m 59.86s 00° 45′ 04.41″ 16.12 270 M?V 0.33 3623±138 unknown 5
TOI-1136 Draco 12h 48m 44.38 s +64° 51′ 18.99″ 9.534 275.8 1.022 5770±50 0.7 6 (1) The planets are in an orbital resonance.[89]
TOI-561 Sextans 09h 52m 44.44s +06° 12′ 57.97″ 10.252 279 G9V 0.785 5455 5 4 (1) -
Kepler-445 Cygnus 19h 54m 57.0s +46° 29′ 55″ 18 294 0.18 3157 unknown 3 -
TOI-763 Centaurus 12h 57m 52.45s −39° 45′ 27.71″ 10.156 311 0.917 5444 6.2 2 (1) -
K2-229 Virgo 12h 27m 29.5848s −06° 43′ 18.7660″ 10.985 335 K2V 0.837 5185 5.4 3
Kepler-102 Lyra 18h 45m 55.9s +47° 12′ 29″ 11.492 340 K3V[90] 0.81 4809 1.41 5
V1298 Tauri Taurus 04h 05m 19.5912s +20° 09′ 25.5635″ 10.31 354 K0-1.5[91] 1.101 4970 0.023 4 This star is a young T Tauri variable.[92]
K2-302 Aquarius 22h 20m 22.7764s −09° 30′ 34.2934″ 11.98 359.3 unknown 3297±73 unknown 3
K2-198 Virgo 13h 15m 22.5s −06° 27′ 54″ 11.0 362 0.8 5213 unknown 3
TOI-125 Hydrus 01h 34m 22.73s −66° 40′ 32.95″ 11.02 363 0.859 5320 unknown 3 (2)
HIP 41378 Cancer 08h 26m 28.0s +10° 04′ 49″ 8.9 378 F8 1.15 6199 unknown 5 (2) Planet f has an unusually low density, and might have rings or an extended atmosphere.[93][94] More planets are still suspected.[95]
Kepler-446 Lyra 18h 49m 00.0s +44° 55′ 16″ 16.5 391 M4V 0.22 3359 unknown 3 -
HD 33142 Lepus 05h 07m 35.54s −13° 59′ 11.34″ 7.96 394.3 1.52 5025+24
−16
unknown 3 Host star is a giant star with spectral type of K0III.[96]
WASP-132 Lupus 14h 30m 26.2s −46° 09′ 33″ 11.938 403 K4V 0.782 4714 7.2 3
K2-148 Cetus 00h 58m 04.28s −00° 11′ 35.36″ 13.05 407 K7V 0.65 4079±70 unknown 3 A secondary red dwarf is gravitationally bound to K2-148.[97]
Kepler-68 Cygnus 19h 24m 07.76s +49° 02′ 25.0″ 8.588 440 G1V 1.079 5793 6.3 3 (1) Planet d, the outermost confirmed planet, is a Jupiter-sized planet which orbits in the habitable zone.[98] Radial velocity measurements discovered an additional signal, which could be a fourth planet or a stellar companion.[99]
HD 28109 Hydrus 04h 20m 57.13s −68° 06′ 09.51″ 9.38 457 1.26 6120±50 unknown 3
COROT-7 Monoceros 06h 43m 49.47s −01° 03′ 46.9″ 11.73 489 K0V 0.93 5275 1.5 3
XO-2 Lynx 07h 48m 07.4814s +50° 13′ 03.2578″ 11.18 496±3 K0V+K0V unknown unknown 6.3 4 Binary with each star orbited by two planets.[100][101]
Kepler-411 Cygnus 19h 10m 25.3s +49° 31′ 24″ 12.5 499.4 K3V 0.83 4974 unknown 5
K2-381 Sagittarius 19h 12m 06.46s −21° 00′ 27.51″ 13.01 505 K2 0.754 4473±138 unknown 3
K2-285 Pisces 23h 17m 32.2s +01° 18′ 01″ 12.03 508 K2V 0.83 4975 unknown 4
K2-32 Ophiuchus 16h 49m 42.2602s −19° 32′ 34.151″ 12.31 510 G9V 0.856 5275 7.9 4 The planets are likely in a 1:2:5:7 orbital resonance.[102]
TOI-1246 Draco 16h 44m 27.96s 70° 25′ 46.70″ 11.6 558 1.12 5217±50 unknown 4
K2-352 Cancer 09h 21m 46.8434s +18° 28′ 10.34710″ 11.12 577 G2V 0.98 5791 unknown 3
Kepler-398 Lyra 19h 25m 52.5s +40° 20′ 38″ 578 K5V 0.72 4493 unknown 3
Kepler-186 Cygnus 19h 54m 36.6s +43° 57′ 18″ 15.29[103] 579.23[104] M1V[105] 0.478 3788 unknown 5 Planet f is the first Earth-size exoplanet discovered that orbits in the habitable zone.[106]
K2-37 Scorpius 16h 13m 48.2445s −24° 47′ 13.4279″ 12.52 590 G3V 0.9 5413 unknown 3
K2-58 Aquarius 22h 15m 17.2364s −14° 02′ 59.3151″ 12.13 596 K2V 0.89 5038 unknown 3
K2-138 Aquarius 23h 15m 47.77s −10° 50′ 58.91″ 12.21 597±55 K1V 0.93 5378±60 2.3 6 Planet g was not fully verified, or could be two long-period planets instead.[107]
K2-38 Scorpius 16h 00m 08.06s −23° 11′ 21.33″ 11.34 630 G3V 1.03 5731±66 unknown 2 (1) Dust disk in system
WASP-47 Aquarius 22h 04m 49.0s −12° 01′ 08″ 11.9 652 G9V 1.084 5400 unknown 4 One planet is a gas giant which orbits in the habitable zone.[108][109] WASP-47 is the only planetary system known to have both planets near the hot Jupiter and another planet much further out.[110]
K2-368 Aquarius 22h 10m 32.58s −11° 09′ 58.02″ 13.54 674 K3 0.746 4663±138 unknown 3 (1)
HAT-P-13 Ursa Major 08h 39m 31.81s +47° 21′ 07.3″ 10.62 698 G4 1.22 5638 5 2 (1) -
Kepler-19 Cygnus 19h 21m 41s +37° 51′ 06″ 15.178 717 G 0.936 5541 1.9 3 System consists of a thick-envelope Super-Earth and two Neptune-mass planets.[111]
Kepler-296 Lyra 19h 06m 09.6s +49° 26′ 14.4″ 12.6 737.113 K7V + M1V[112] unknown 4249 unknown 5 All planets orbit around the primary star.[113] Planets e and f are potentially habitable.[113]
Kepler-454 Lyra 19h 09m 55.0s +38° 13′ 44″ 11.57 753 G 1.028 5687 5.25 3
Kepler-25 Lyra 19h 06m 33.0s +39° 29′ 16″ 11 799 F[114] 1.22 6190 unknown 3 Two planets were discovered by transit-timing variations,[115] and the third planet was discovered by follow-up radial velocity measurements.[116]
Kepler-114 Cygnus 19h 36m 29.0s +48° 20′ 58″ 13.7 846 K 0.71 4450 unknown 3
Kepler-54 Cygnus 19h 39m 06.0s +43° 03′ 23″ 16.3 886 M 0.52 3705 unknown 3
Kepler-20 Lyra 19h 10m 47.524s 42° 20′ 19.30″ 12.51 950 G8V 0.912 5466 8.8 6 Planets e and f were the first Earth-sized planets to be discovered.[117]
K2-19 Virgo 11h 39m 50.4804s +00° 36′ 12.8773″ 13.002 976 K0V[118] or G9V[119] 0.918 5250±70 8 3 -
PSR B1257+12 Virgo 13h 00m 03.58s +12° 40′ 56.5″ 24.31 980 pulsar 1.444 28856 0.797 3 Only pulsar with a multiplanetary system, and first exoplanets and multiplanetary system to be confirmed.[120][121] Star with dimmest apparent magnitude to have a multiplanetary system.
Kepler-62 Lyra 18h 52m 51.060s +45° 20′ 59.507″ 13.75[122] 990 K2V[122] 0.69 4925 7 5 Planets e and f orbit in the habitable zone.[122][123]
Kepler-48 Cygnus 19h 56m 33.41s +40° 56′ 56.47″ 13.04 1000 K 0.88 5190 unknown 5
Kepler-100 Lyra 19h 25m 32.6s +41° 59′ 24″ 1011 G1IV 1.109 5825 6.5 4
Kepler-49 Cygnus 19h 29m 11.0s +40° 35′ 30″ 15.5 1015 K 0.55 3974 unknown 4
Kepler-65 Lyra 19h 14m 45.3s +41° 09′ 04.2″ 11.018 1019 F6IV 1.199 6211 unknown 4 -
Kepler-52 Draco 19h 06m 57.0s +49° 58′ 33″ 15.5 1049 K 0.58 4075 unknown 3
K2-314 Libra 15h 13m 00.0s −16° 43′ 29″ 11.4 1059 G8IV/V 1.05 5430 9 3
K2-219 Pisces 00h 51m 22.9s +08° 52′ 04″ 12.09 1071 G2 1.02 5753±50 unknown 3
K2-268 Cancer 08h 54m 50.2862s +11° 50′ 53.7745″ 13.85 1079 unknown unknown unknown 5
K2-183 Cancer 08h 20m 01.7184s 14° 01′ 10.0711″ 12.85 1083 unknown 5482±50 unknown 3
K2-187 Cancer 08h 50m 05.6682s 23° 11′ 33.3712″ 12.864 1090 G?V 0.967 5438±63 unknown 4
Kepler-1542 Lyra 19h 02m 54.8s +42° 39′ 16″ 1096 G5V 0.94 5564 unknown 4 (1) -
Kepler-26 Lyra 18h 59m 46s +46° 34′ 00″ 16 1100 M0V 0.65 4500 unknown 4 Transiting exoplanets[124] which are low-density planets below the size of Neptune.[125][126]
Kepler-167 Cygnus 19h 30m 38.0s +38° 20′ 43″ 1119 ± 6 0.76 4796 unknown 4 Planet e is the first transiting Jupiter analog discovered.[127][128]
Kepler-81 Cygnus 19h 34m 32.9s +42° 49′ 30″ 15.56 1136 K?V 0.648 4391 unknown 3
Kepler-132 Lyra 18h 52m 56.6s +41° 20′ 35″ 1140 F9 0.98 6003 unknown 4
Kepler-80 Cygnus 19h 44m 27.0s +39° 58′ 44″ 14.804 1218 M0V[129] 0.73 4250 unknown 6 Red dwarf star with six confirmed planets.[130][131] Five of them are in an orbital resonance.[132][131]
Kepler-159 Cygnus 19h 48m 16.8s +40° 52′ 08″ 1219 K 0.63 4625 unknown 2 (1) Star has a very low metallicity.
K2-299 Aquarius 22h 05m 06.5342s −14° 07′ 18.0135″ 13.12 1220 unknown 5724±72 unknown 3
Kepler-88 Lyra 19h 24m 35.5431s +40° 40′ 09.8098″ 13.5 1243 G8IV 1.022 5513±67 2.45 3
Kepler-174 Lyra 19h 09m 45.4s +43° 49:56′ 1269 K unknown 4880 unknown 3 Planet d may orbit in the habitable zone.
Kepler-83 Lyra 18h 48m 55.8s +43° 39′ 56″ 16.51 1306 K7V 0.664 4164 unknown 3
TOI-1338 Pictor 06h 08m 31.97s +59° 32′ 28.1″ 11.72 1318 F8
M
1.127 6160 4.4 2 (0)
Kepler-271 Lyra 18h 52m 00.7s +44° 17′ 03″ 1319 G7V 0.9 5524 unknown 3 Metal-poor star
Kepler-169 19h 03m 60.0s +40° 55:10′ 12.186 1326 K2V 0.86 4997 unknown 5
Kepler-451 Cygnus 19h 38m 32.61s 46° 03′ 59.1″ 1340 sdB
M
0.6 29564 6 3 Three circumbinary planets orbit around the Kepler-451 binary pair.[133]
Kepler-304 Cygnus 19h 37m 46.0s +40° 33′ 27″ 1418 K 0.8 4731 unknown 4
Kepler-18 Cygnus 19h 52m 19.06s +44° 44′ 46.76″ 13.549 1430 G7V 0.97 5345 10 3
Kepler-106 Cygnus 20h 03m 27.4s +44° 20′ 15″ 12.882 1449 G1V 1 5858 4.83 4
Kepler-92 Lyra 19h 16m 21.0s +41° 33′ 47″ 11.6 1463 G1IV 1.209 5871 5.52 3
Kepler-450 Cygnus 19h 41m 56.8s +51° 00′ 49″ 11.684 1487 F 1.19 6152 unknown 3
Kepler-89 Cygnus 19h 49m 20.0s +41° 53′ 28″ 12.4 1580 F8V 1.25 6116 3.9 4 Farthest F-type main sequence star from the Sun with a multiplanetary system. One study found hints of additional planets orbiting Kepler-89.[134]
Kepler-1388 Lyra 18h 53m 20.6s +47° 10′ 28″ 1604 0.63 4098 unknown 4 (1) -
K2-282 Pisces 00h 53m 43.6833s 07° 59′ 43.1397″ 14.04 1638 G?V 0.94 5499±109 unknown 3
Kepler-107 Cygnus 19h 48m 06.8s +48° 12′ 31″ 12.7 1714 G2V[135] 1.238 5851 4.29 4 -
Kepler-176 Cygnus 19h 38m 40.3s +43° 51′ 12″ 1746[136] unknown 5232 unknown 4
Kepler-1047 Cygnus 19h 14m 35.1s +50° 47′ 20″ 1846 G2V 1.08 5754 unknown 3 -
Kepler-55 Lyra 19h 00m 40.0s +44° 01′ 35″ 16.3 1888 K 0.62 4362 unknown 5 Planet c may orbit in the inner habitable zone.
Kepler-166 Cygnus 19h 32m 38.4s +48° 52′ 52″ 1968 G 0.88 5413 unknown 3
Kepler-11 Cygnus 19h 48m 27.62s +41° 54′ 32.9″ 13.69 2150 ±20 G6V[137] 0.954 5681 7.834 6 Farthest star from the Sun with exactly six exoplanets. First system discovered with six transiting planets.[137] The planets have low densities.[138]
Kepler-1254 Draco 19h 34m 59.3s +45° 06′ 26″ 2205 0.78 4985 unknown 3 -
Kepler-289 Cygnus 19h 49m 51.7s +42° 52′ 58″ 12.9 2283 G0V 1.08 5990 0.65 3 -
Kepler-85 Cygnus 19h 23m 54.0s +45° 17′ 25″ 15.0 2495 G 0.92 5666 unknown 4
Kepler-157 Lyra 19h 24m 23.3s +38° 52′ 32″ 2523 G2V 1.02 5774 unknown 3
Kepler-342 Cygnus 19h 24m 23.3s +38° 52′ 32″ 2549 F 1.13 6175 unknown 4
Kepler-148 Cygnus 19h 19m 08.7s +46° 51′ 32″ 2580 K?V 0.83 5019.0±122.0 unknown 3
Kepler-51 Cygnus 19h 45m 55.0s +49° 56′ 16″ 15.0 2610 G?V 1 5803 unknown 4 Super-puff planets with some of the lowest densities known.[139]
Kepler-403 Cygnus 19h 19m 41.1s +46° 44′ 40″ 2741 F9IV-V 1.25 6090 unknown 3
Kepler-9 Lyra 19h 02m 17.76s +38° 24′ 03.2″ 13.91 2754 G2V 0.998 5722 3.008 3 First multiplanetary system to be discovered by the Kepler Space Telescope.[140][141]
Kepler-23 Cygnus 19h 36m 52.0s +49° 28′ 45″ 14 2790 G5V 1.11 5760 unknown 3 -
Kepler-46 Cygnus 19h 17m 05.0s +42° 36′ 15″ 15.3 2795 K?V 0.902 5155 9.9 3 -
Kepler-305 Cygnus 19h 56m 53.83s +40° 20′ 35.46″ 15.812 2833 K 0.85 4918 unknown 3 (1)
Kepler-90 Draco 18h 57m 44.0s +49° 18′ 19″ 14.0 2840 ± 40 F9 IV/V 1.13 5930 2 8 All eight exoplanets are larger than Earth and are within 1.1 AU of the parent star. Only star apart from the Sun with at least eight planets.[142] A Hill stability test shows that the system is stable.[143] Planet h orbits in the habitable zone.
Kepler-150 Lyra 19h 12m 56.2s +40° 31′ 15″ 2906 G?V 0.97 5560 unknown 5 Planet f orbits in the habitable zone.
Kepler-82 Cygnus 19h 31m 29.61s +42° 57′ 58.09″ 15.158 2949 G?V 0.91 5512 unknown 5
Kepler-154 Cygnus 19h 19m 07.3s +49° 53′ 48″ 2985 G3V 0.98 5690 unknown 5
Kepler-56 Cygnus 19h 35m 02.0s +41° 52′ 19″ 13 3060 K?III 1.32 4840 3.5 3
Kepler-350 Lyra 19h 01m 41.0s +39° 42′ 22″ 13.8 3121 F 1.03 6215 unknown 3
Kepler-603 Cygnus 19h 37m 07.4s +42° 17′ 27″ 3134 G2V 1.01 5808 unknown 3 -
Kepler-160 Lyra 19h 11m 05.65s +42° 52′ 09.5″ 13.101 3140 G2V unknown 5470 unknown 3 (1) The unconfirmed planet Kepler-160e (or KOI-456.04) is a potentially habitable planet.[144]
Kepler-401 Cygnus 19h 20m 19.9s +50° 51′ 49″ 3149 F8V 1.17 6117 unknown 3
Kepler-58 Cygnus 19h 45m 26.0s +39° 06′ 55″ 15.3 3161 G1V 1.04 5843 unknown 3
Kepler-79 Cygnus 20h 02m 04.11s +44° 22′ 53.69″ 13.914 3329 F 1.17 6187 unknown 4
Kepler-60 Cygnus 19h 15m 50.70s +42° 15′ 54.04″ 13.959 3343 G 1.04 5915 unknown 3
Kepler-122 19h 24m 26.9s +39° 56′ 57″ 3351 F 1.08 6050 unknown 5
Kepler-279 Lyra 19h 09m 34.0s +42° 11′ 42″ 13.7 3383 F 1.1 6562 unknown 3
Kepler-255 Cygnus 19h 44m 15.4s +45° 58′ 37″ 3433 G6V 0.9 5573 unknown 3
Kepler-47 Cygnus 19h 41m 11.5s +46° 55′ 13.69″ 15.178 3442 G
M
1.043 5636(A)
(B is unknown)
4.5 3 Circumbinary planets, with one of the planets orbiting in the habitable zone.[145][146][147]
Kepler-292 19h 43m 03.84s +43° 25′ 27.4″ 13.97 3446 K0V 0.85 5299 unknown 5
Kepler-27 Cygnus 19h 28m 56.82s +41° 05′ 9.15″ 15.855 3500 G5V 0.65 5400 unknown 3
Kepler-351 Lyra 19h 05m 48.6s +42° 39′ 28″ 3535 G?V 0.89 5643 unknown 3
Kepler-276 Cygnus 19h 34m 16s +39° 02′ 11″ 15.368 3734 G?V 1.1 5812 unknown 3
Kepler-24 Lyra 19h 21m 39.18s +38° 20′ 37.51″ 14.925 3910 G1V 1.03 5800 unknown 4 -
Kepler-87 Cygnus 19h 51m 40.0s +46° 57′ 54″ 15 4021 G4IV 1.1 5600 7.5 2 (2) Farthest system from the Sun with an unconfirmed exoplanet candidate.
Kepler-33 Lyra 19h 16m 18.61s +46° 00′ 18.8″ 13.988 4090 G1IV 1.164 5849 4.27 5
Kepler-282 Lyra 18h 58m 43.0s +44° 47′ 51″ 15.2 4363 G?V 0.97 5876 unknown 4
Kepler-758 Cygnus 19h 32m 20.3s +41° 08′ 08″ 4413 1.16 6228 unknown 4 Farthest system from the Sun with exactly four confirmed exoplanets.
Kepler-53 Lyra 19h 21m 51.0s +40° 33′ 45″ 16 4455 G?V 0.98 5858 unknown 3
Kepler-30 Lyra 19h 01m 08.07s +38° 56′ 50.21″ 15.403 4560 G6V 0.99 5498 unknown 3
Kepler-84 Cygnus 19h 53m 00.49s +40° 29′ 45.87″ 14.764 4700 G3IV 1 5755 unknown 5
Kepler-385 Cygnus 19h 37m 21.23s +50° 20′ 11.55″ 15.76 4900 F8V 0.99 5835 unknown 3 (4)
Kepler-31 Cygnus 19h 36m 06.0s +45° 51′ 11″ 15.5 5429 F 1.21 6340 unknown 3 The three planets are in an orbital resonance.[148]
Kepler-32 Cygnus 19h 51m 22.2s +46° 34′ 27″ M1V 0.58 3900 unknown 5 Planet f is smaller than Earth.
Kepler-238 Lyra 19h 11m 35s +40° 38′ 16″ 15.084 5867 G5IV 1.06 5614 unknown 5 One of the farthest systems from the Sun with a multiplanetary system, and the farthest system where exoplanets were discovered by the Kepler space telescope.
Kepler-245 Cygnus 19h 26m 33.4s +42° 26′ 11″ 0.8 5100 unknown 4
Kepler-218 Cygnus 19h 41m 39.1s +46° 15′ 59″ unknown 5502 unknown 3
Kepler-217 Cygnus 19h 32m 09.1s +46° 16′ 39″ unknown 6171 unknown 3
Kepler-192 Lyra 19h 11m 40.3s +45° 35′ 34″ unknown 5479 unknown 3
Kepler-191 Cygnus 19h 24m 44.0s +45° 19′ 23″ 0.85 5282 unknown 3
Kepler-431 Lyra 18h 44m 26.9s +43° 13′ 40″ 1.071 6004 unknown 3
Kepler-338 Lyra 18h 51m 54.9s +40° 47′ 04″ 1.1 5923 unknown 4
Kepler-197 Cygnus 19h 40m 54.3s +50° 33′ 32″ unknown 6004 unknown 4
Kepler-247 Lyra 19h 14m 34.2s +43° 02′ 21″ 0.884 5094 unknown 3
Kepler-104 Lyra 19h 10m 25.1s +42° 10′ 00″ 0.81 5711 unknown 3 -
Kepler-126 Cygnus 19h 17m 23.4s +44° 12′ 31″ unknown 6239 unknown 3 -
Kepler-127 Lyra 19h 00m 45.6s +46° 01′ 41″ unknown 6106 unknown 3 -
Kepler-130 Lyra 19h 13m 48.2s +40° 14′ 43″ 1 5884 unknown 3 -
Kepler-164 Lyra 19h 11m 07.4s +47° 37′ 48″ 1.11 5888 unknown 3 -
Kepler-171 Cygnus 19h 47m 05.3s +41° 45′ 20″ unknown 5642 unknown 3 -
Kepler-172 Lyra 19h 47m 05.3s +41° 45′ 20″ 0.86 5526 unknown 4 -
Kepler-149 Lyra 19h 03m 24.9s +38° 23′ 03″ unknown 5381 unknown 3
Kepler-142 Cygnus 19h 40m 28.5s +48° 28′ 53″ 0.99 5790 unknown 3
Kepler-124 Draco 19h 07m 00.7s +49° 03′ 54″ unknown 4984 unknown 3
Kepler-402 Lyra 19h 13m 28.9s +43° 21′ 17″ unknown 6090 unknown 4 (1)
Kepler-399 Cygnus 19h 58m 00.4s +40° 40′ 15″ unknown 5502 unknown 3
Kepler-374 Cygnus 19h 36m 33.1s +42° 22′ 14″ 0.84 5977 unknown 3
Kepler-372 Cygnus 19h 25m 01.5s +49° 15′ 32″ 1.15 6509 unknown 3
Kepler-363 Lyra 18h 52m 46.1s +41° 18′ 19″ 1.23 5593 unknown 3
Kepler-359 Cygnus 19h 33m 10.5s +42° 11′ 47″ 1.07 6248 unknown 3
Kepler-357 Cygnus 19h 24m 58.3s +44° 00′ 31″ 0.78 5036 unknown 3
Kepler-354 Lyra 19h 03m 00.4s +41° 20′ 08″ 0.65 4648 unknown 3
Kepler-206 Lyra 19h 26m 32.3s +41° 50′ 02″ 0.94 5764 unknown 3
Kepler-203 Cygnus 19h 01m 23.3s +41° 45′ 43″ 0.98 5821 unknown 3
Kepler-194 Cygnus 19h 27m 53.1s +47° 51′ 51″ unknown 6089 unknown 3
Kepler-184 Lyra 19h 27m 48.5s +43° 04′ 29″ unknown 5788 unknown 3
Kepler-178 Lyra 19h 08m 24.3s +46° 53′ 47″ unknown 5676 unknown 3
Kepler-336 Lyra 19h 20m 57.0s +41° 19′ 53″ 0.89 5867 unknown 3
Kepler-334 Lyra 19h 08m 33.8s +47° 06′ 55″ 1 5828 unknown 3
Kepler-332 Lyra 19h 06m 39.1s +47° 24′ 49″ 0.8 4955 unknown 3
Kepler-331 Lyra 19h 27m 20.2s +39° 18′ 26″ 0.51 4347 unknown 3
Kepler-327 Cygnus 19h 30m 34.2s 44° 05′ 16″ 0.55 3799 unknown 3
Kepler-326 Cygnus 19h 37m 18.1s +46° 00′ 08″ 0.98 5105 unknown 3
Kepler-325 Cygnus 19h 19m 20.5s +49° 49′ 32″ 0.87 5752 unknown 3

Stars orbited by both planets and brown dwarfs

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See also

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Notes

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
A multiplanetary system is a stellar system featuring two or more gravitationally bound planets orbiting a central star, distinct from single-planet configurations and providing insights into planetary formation and dynamics. Such systems are cataloged based on confirmed detections, primarily through astronomical surveys that verify multiple planets via techniques like transit photometry, which measures dips in stellar brightness caused by orbiting planets, and radial velocity measurements, which detect stellar wobbles induced by planetary gravity. The list encompasses the Solar System—our own multiplanetary example with eight planets—as well as exoplanetary systems beyond it, focusing on those with robust evidence to exclude false positives or unconfirmed candidates. As of late , over 6,000 have been confirmed across roughly 4,500 unique host stars, with more than 1,000 of these stars hosting multiple planets, representing a significant fraction of known exoplanetary architectures. Key missions driving these discoveries include NASA's , which identified hundreds of multiplanetary systems through its focus on transiting planets, and the (TESS), which continues to expand the catalog with nearby examples. Notable systems in the list include , an star with seven Earth-sized rocky planets in a compact , offering prime targets for studies, and , a Sun-like star with eight planets, the first confirmed via analysis of archival data. These multiplanetary systems reveal diverse architectures, from closely packed "peas-in-a-pod" configurations resembling those found by Kepler to resonant chains like those in TOI-178, where orbital periods align in stable ratios, challenging models of and stability. Ongoing observations with the are enhancing characterizations, particularly for atmospheres in multiplanet setups around nearby stars, advancing our understanding of how common or unique our Solar System's layout may be.

Introduction to Multiplanetary Systems

Definition and Criteria

A multiplanetary system, in the context of astronomy, consists of a host star orbited by two or more confirmed , distinguishing it from single-planet systems. These systems provide insights into planetary formation and dynamics, as multiple planets can interact gravitationally, influencing orbital stability and architecture. Unlike our Solar System, which features eight planets, exoplanetary multiplanetary systems often exhibit compact configurations with short-period orbits, particularly those detected by transit surveys. For a system to be classified as multiplanetary in catalogs, each planet must meet stringent confirmation criteria established by authoritative archives such as NASA's Exoplanet Archive. A confirmed is defined as a non-stellar body with a (or minimum ) of 30 masses or less, bound in orbit around its host star rather than free-floating. It requires sufficient follow-up observations to validate the detection and rule out false positives, such as eclipsing binaries or instrumental artifacts, along with publication of orbital and physical properties in peer-reviewed astrophysical literature. Detection methods contributing to confirmation include transit photometry, radial velocity measurements, direct imaging, and astrometry, often requiring multiple independent verifications for reliability. Systems are included in lists only if all constituent planets satisfy these standards; candidate planets without full confirmation are noted separately but do not count toward multiplicity. Discovery credit is assigned to the first peer-reviewed publication, with independent confirmations acknowledged if reported promptly. This rigorous process ensures that listed multiplanetary systems, numbering over 1,000 as of recent counts, represent robustly verified examples rather than speculative detections.

Historical Development

The discovery of multiplanetary systems began with the identification of the first confirmed exoplanets orbiting the in 1992. Using precise pulsar timing observations from the Arecibo , astronomers Aleksander Wolszczan and Dale Frail detected periodic variations in the pulsar's signal indicative of two -mass planets in stable orbits, marking the inaugural detection of any extrasolar and the first multiplanetary configuration. A third , with a mass approximately 0.015 masses, was confirmed in 1994 through additional timing data, solidifying as a three- system formed likely from the remnants of a disrupted companion star. This groundbreaking finding, though around an exotic host unlike Sun-like stars, established the existence of beyond the Solar System and prompted searches for companions around normal stars. The transition to multiplanetary systems around main-sequence stars occurred in 1999, when radial velocity measurements revealed three Jupiter-mass planets orbiting the Sun-like star Upsilon Andromedae (υ Andromedae). Led by teams at the California and Carnegie Planet Search, observations from the Hamilton Echelle Spectrograph at Lick Observatory and the HIRES spectrograph at Keck Observatory detected velocity perturbations corresponding to planets with minimum masses of 0.69, 1.99, and 4.01 Jupiter masses, in orbits ranging from 4.62 days to about 3.52 years. This was the first confirmed multiplanetary system around a main-sequence star, demonstrating that close-in hot Jupiters could coexist with outer companions in resonant or scattered configurations, challenging models of planetary formation and migration. Shortly thereafter, similar radial velocity surveys identified additional systems, such as 55 Cancri with its second confirmed planet in 2002, expanding the catalog to dozens by the mid-2000s and highlighting the prevalence of giant planets in multiplanet architectures. The advent of space-based transit photometry revolutionized the detection of multiplanetary systems in the late 2000s and 2010s. NASA's Kepler mission, launched in 2009, identified the first confirmed multi-transiting system in 2010 (Kepler-9), revealing two Saturn-mass planets in a , and ultimately cataloged over 700 multiplanet systems by mission end in 2018, comprising about one-third of all confirmed exoplanets at the time. These discoveries, primarily around cool dwarf stars, demonstrated that compact, coplanar systems with multiple small planets are common, with orbital periods often under 100 days and architectures resembling scaled-down Solar System analogs. Subsequent missions like TESS (launched 2018) have added hundreds more, while ground-based follow-up has refined masses and stabilities. By November 2025, over 1,000 confirmed multiplanetary systems are known, underscoring their ubiquity and informing theories on disk evolution and dynamical interactions.

Detection and Confirmation Methods

Transit Photometry and Variability

Transit photometry is a primary method for detecting exoplanets by measuring the periodic decrease in a star's brightness as a passes in front of it, known as a transit. This technique is particularly effective for identifying multiplanetary systems when multiple distinct transit signals appear in the photometric of a single star, allowing astronomers to infer the presence of several orbiting bodies. The depth of each transit provides information on the planet's radius relative to the star, while the timing and duration reveal orbital periods and inclinations. For multiplanetary systems, the alignment of multiple ' orbital planes close to the enables simultaneous detection, which occurs in about 0.5% of systems surveyed by space-based telescopes. The revolutionized the detection of multi-transiting systems through high-precision, continuous photometry of over 150,000 stars, identifying more than 700 confirmed multiplanetary systems by the end of its primary mission in 2013. Early discoveries, such as the system with six transiting planets announced in 2011, demonstrated the method's power to reveal compact architectures with periods ranging from 0.4 to 127 days. In these systems, the folded light curves separate individual transits, but interactions like transit timing variations (TTVs) arise from gravitational perturbations among planets, providing dynamical confirmation without follow-up. The multiplicity of signals also reduces false positive rates, as the probability of multiple independent astrophysical mimics (e.g., eclipsing binaries) is low, with statistical validation showing false positive probabilities below 1% for many candidates. Stellar variability poses a significant challenge to transit photometry in multiplanetary systems, as intrinsic brightness fluctuations from starspots, , or can mimic or obscure shallow transit signals, especially for small planets with depths below 1 mmag. In Kepler data, stars hosting small exoplanets (radii ≤ 2.5 R⊕) exhibit variability on short timescales (e.g., 0.25 days) that raises the , limiting detection to the quietest hosts with rms scatter ≤ 0.5 mmag. For instance, solar-like stars in multiplanetary configurations show variability amplitudes of 50–250 ppm depending on magnitude, with brighter, less active subgiants (e.g., Kepler-21) enabling clearer detection of Earth-sized planets despite jitter. Correcting for such variability through multi-epoch modeling or filtering is essential, as uncorrected activity can bias transit depths by up to 20% and complicate TTV analysis in resonant systems. Ongoing missions like TESS and build on Kepler by targeting quieter stars to mitigate these effects.

Radial Velocity and Astrometry

The (RV) method detects exoplanets by observing the periodic Doppler shift in a host star's spectral lines, resulting from the star's reflex motion due to the gravitational influence of orbiting planets. This technique measures the star's velocity along the , typically with precisions of meters per second using high-resolution spectrographs like HARPS or HIRES. For multiplanetary systems, the combined gravitational perturbations produce a composite velocity curve that can be decomposed into multiple Keplerian signals through or periodogram techniques, such as the Lomb-Scargle algorithm, allowing the identification of distinct orbital periods and minimum masses for each planet. This approach has been instrumental in discovering many multiplanetary systems, particularly those with massive, close-in planets. A seminal example is the system, where RV observations from 1996 to 2007 revealed five with orbital periods ranging from 0.7 days to 14.6 years, demonstrating the method's ability to resolve hierarchical architectures despite overlapping signals. The RV method excels in providing like eccentricity and semi-major axis, offering insights into system dynamics, but it yields only minimum (msinim \sin i) due to the unknown inclination angle ii, and it is sensitive to stellar activity noise that can mimic planetary signals. As of November 2025, the RV method has confirmed 1,157 exoplanets, with approximately 20% in multiplanetary configurations, highlighting its role in probing planet formation theories through mass ratios and resonances. Astrometry complements RV by directly measuring the star's positional displacement on the sky plane, caused by the photocenter's wobble from unseen , typically requiring microarcsecond precision. In multiplanetary systems, the stellar trajectory manifests as a superposition of elliptical motions, which advanced orbital fitting models can disentangle to derive true masses, inclinations, and arguments of periastron without the sini\sin i degeneracy. This method is particularly suited for detecting long-period, massive in wide orbits, where RV signals become , and it enables full 3D orbital characterization for dynamical studies. Although has historically yielded few detections due to instrumental limits—none in multiplanetary systems as of November 2025—the mission has revolutionized the field with its billion-star catalog. 's Data Release 3 (2022) enabled the first confirmed astrometric , HIP 66074 b (also known as Gaia-3b), a of approximately 20 masses orbiting a young star, though single-planet cases dominate; recent 2025 confirmations include Gaia-4b, another massive planet around a low-mass star. Simulations predict could detect up to 20 multiplanetary systems by mission end, primarily around nearby, quiet stars. Limitations include sensitivity to only the most massive companions (typically >1 at >1 AU) and challenges from galactic differential rotation, but future missions like may expand detections to dozens of multiplanet architectures, aiding in validating RV candidates and exploring system stability.

Catalogues of Confirmed Systems

Systems Hosted by Main-Sequence Stars

Multiplanetary systems hosted by main-sequence stars represent the majority of confirmed configurations, as these stars—characterized by stable hydrogen fusion in their cores and spectral types from O to —provide environments conducive to planet formation and detection via methods like transit photometry and measurements. These systems often exhibit compact architectures with planets orbiting close to their host stars, reflecting formation processes in protoplanetary disks where migration and dynamical interactions shape orbital resonances and spacing. The majority of the over 1,000 confirmed multiplanetary systems as of late 2025 are hosted by main-sequence stars, predominantly around Sun-like G and K-type stars, though red dwarfs (-types) host a significant fraction due to their and the sensitivity of transit surveys. The Kepler mission has been instrumental in identifying many of these systems, revealing that multiplanet occurrences are common, with about 30-50% of Sun-like stars hosting at least two planets based on statistical analyses of transit data. Notable examples include the system around an ultracool M8 dwarf, which features seven Earth-sized planets in a compact chain of mean-motion resonances, all within 0.06 AU of the star, highlighting the potential for habitable zones in low-mass stellar environments. Another prominent case is the system, orbiting a K2V star, with six planets—ranging from to sizes—packed within 0.5 AU, demonstrating tight orbital packing and possible tidal evolution. Larger-scale surveys, such as those from the Transiting Exoplanet Survey Satellite (TESS), continue to expand this catalog, confirming systems like TOI-178, a six-planet chain around a K7V star with periods from 1.9 to 20.7 days and a Laplace resonance involving the inner three planets, underscoring dynamical stability in resonant configurations. For higher-mass main-sequence stars, the HR 8799 system around an A5V youth (age ~30 Myr) hosts four gas giants detected via direct imaging and confirmed by astrometry, with masses 5-13 Jupiter masses and semi-major axes from 15 to 68 AU, providing insights into giant planet formation via core accretion or disk instability. These diverse architectures illustrate how stellar properties influence planet multiplicity, with cooler, lower-mass stars favoring compact terrestrial systems and hotter stars enabling wider-orbit giants.
System NameHost Star TypeNumber of Confirmed PlanetsKey FeaturesDiscovery Method
M8V7Earth-sized, resonant chain, habitable zone planetsTransit (Spitzer, ground-based)
K2V6Compact (<0.5 AU), super-Earths to mini-NeptunesTransit (Kepler)
TOI-178K7V6Laplace resonance in inner planets, periods 1.9-20.7 daysTransit (TESS, CHEOPS)
HR 8799A5V4Gas giants, wide orbits (15-68 AU), young systemDirect imaging (Gemini, Keck)
HD 219134K3V6Mix of rocky and gaseous planets, inner super-EarthsRadial velocity (HARPS-N) + Transit (TESS)
This table highlights representative systems, emphasizing the range from ultra-compact to extended architectures around main-sequence hosts. Ongoing missions like PLATO and JWST are expected to refine multiplicities and characterize atmospheres, further elucidating formation mechanisms.

Systems Hosted by Evolved Stars

Multiplanetary systems hosted by evolved stars, including subgiants, red giants, and asymptotic giant branch stars, represent a critical phase in planetary system evolution, where stellar expansion and mass loss influence orbital dynamics and planetary survival. These systems are rarer in catalogs compared to those around main-sequence hosts due to observational challenges: the larger stellar radii reduce transit probabilities and dilute signals, while stellar pulsations complicate radial velocity measurements. Nonetheless, detections via transit photometry from missions like Kepler and K2, combined with radial velocity follow-up, have confirmed several such systems, revealing compact architectures and potential orbital migration induced by the host's evolution. A prominent example is the Kepler-56 system, orbiting a K5-type red giant approximately 3,000 light-years away with a mass of 1.3 solar masses and radius four times that of the Sun. This system features three confirmed planets: the inner two, Kepler-56b and c, are Neptune-sized (radii ~4 and ~7 Earth radii, respectively) in close orbits (periods of 10.5 and 21.4 days), while the outer Kepler-56d is a Jupiter-mass gas giant (mass ~5.6 Jupiter masses) at 2.2 AU with a 1,002-day period. Notably, the inner planets' orbits are misaligned with the star's equator by ~45 degrees, likely due to gravitational perturbations from the outer companion during the host's expansion, demonstrating dynamical stability amid stellar evolution; the system is projected to engulf the inner planets in about 130-155 million years. Another well-characterized system is EPIC 249893012, a G8-type subgiant host with a mass of 1.1 solar masses and radius of 2.3 solar radii, located ~1,100 light-years distant. It hosts three transiting planets detected by K2: a super-Earth (EPIC 249893012 b, radius 1.6 Earth radii, period 3.4 days), and two sub-Neptunes (c and d, radii ~3.5 and ~2.8 Earth radii, periods 5.7 and 8.3 days, respectively). The planets form a compact chain with orbital periods in a near-3:2 resonance, suggesting formation similar to main-sequence compact systems but with evidence of inward migration post-main-sequence. The host's moderate evolution allows survival of these close-in worlds, though future expansion may disrupt the configuration. Radial velocity surveys have uncovered additional multiplanetary systems around red giants, often featuring massive gas giants at wider separations. For instance, HD 4732 (a K0 giant, mass 1.7 solar masses, radius 5.4 solar radii) hosts two Jupiter-mass planets at 1.2 and 4.6 AU, with the inner one residing in the conservative despite the host's luminosity. Similarly, HIP 67851 (K2 giant, mass 1.6 solar masses, radius 5.9 solar radii) has planets at 0.5 and 3.8 AU, the outer in the optimistic . These systems highlight a preference for massive planets around metal-rich giants, with orbital separations scaled outward compared to main-sequence analogs, possibly due to disk evolution during the subgiant phase. Other examples include HD 1605, HD 95089, HIP 5364, and HIP 24275, each with two gas giants, underscoring that ~10-20% of giant stars may host multiple planets based on current surveys.
SystemHost Spectral TypeNumber of PlanetsKey FeaturesDistance (ly)
Kepler-56K5 III3Misaligned inner transiting sub-Neptunes; outer gas giant; dynamical perturbations~3,000
EPIC 249893012G8 IV3Compact transiting super-Earth + sub-Neptunes; near-resonant chain~1,100
HD 4732K0 III2Two Jupiter-mass giants; inner in habitable zone~250
HIP 67851K2 III2Close-in and distant gas giants; outer in optimistic HZ~430
These detections, primarily from Kepler, K2, and ground-based radial velocity programs like EXPRESS, indicate that planetary systems can endure the red giant phase, with outer planets potentially capturing debris from engulfed inner bodies. However, the small sample (fewer than 30 known systems as of 2025) reflects biases toward brighter, nearby giants; future missions like PLATO may expand the catalog, probing habitability around evolving hosts.

Systems Involving Brown Dwarfs

Stars with Both Planets and Brown Dwarfs

Stars that host both confirmed exoplanets and brown dwarfs represent a rare class of multiplanetary systems, where the central star supports companions spanning the planetary and substellar regimes. These systems challenge traditional models of companion formation due to the observed scarcity of brown dwarfs in close orbits around Sun-like stars, often termed the "brown dwarf desert." Detection typically relies on radial velocity measurements for inner planets and direct imaging or astrometry for outer brown dwarfs, given their wider separations. As of 2025, approximately 15 such systems are confirmed, primarily around main-sequence FGK stars, with brown dwarfs generally orbiting at separations exceeding 10 AU to avoid dynamical instabilities with inner planets. One of the earliest examples is the HD 3651 system, a G3V star at 32 light-years in Pisces. It hosts an inner Jupiter-mass planet, HD 3651 b (m sin i ≈ 0.6 M_Jup, P ≈ 62 days, a ≈ 0.28 AU), detected via radial velocity in 2001. A T8-type brown dwarf companion, HD 3651 B (mass 20–60 M_Jup, T_eff ≈ 800 K, separation ≈ 440 AU), was directly imaged in 2006 using adaptive optics on ESO telescopes, marking the first such imaged brown dwarf around an exoplanet host. The wide orbit of the brown dwarf suggests it formed independently before capture, preserving the inner planet's stability. The HD 168443 system, centered on a K3V star 145 light-years away in Serpens, features a hot Jupiter, HD 168443 b (m sin i ≈ 7.8 M_Jup, P ≈ 4.7 days, a ≈ 0.07 AU), discovered in 1999 via radial velocity. An outer companion, HD 168443 c (m sin i ≈ 18 M_Jup, P ≈ 4.1 years, a ≈ 2.5 AU), was identified in 2000 and classified as a brown dwarf based on its minimum mass and orbital dynamics, confirmed by later astrometric data. This configuration highlights potential migration scenarios, as the brown dwarf's proximity could perturb the inner planet over long timescales.
SystemHost Star TypeInner Planet DetailsBrown Dwarf DetailsSeparation (AU)Primary Reference
HD 3651G3VHD 3651 b: ~0.6 M_Jup, P=62 dHD 3651 B: 20–60 M_Jup, T8 dwarf~440Mugrauer et al. (2006)
HD 168443K3VHD 168443 b: ~7.8 M_Jup, P=4.7 dHD 168443 c: ~18 M_Jup min~2.5Marcy et al. (2000)
HD 38529G4IVHD 38529 b: ~1.2 M_Jup, P=14.3 dHD 38529 c: ~37 M_Jup, L1 dwarf~3.7Fischer et al. (2003)
HD 4113G5VHD 4113 A b: ~1.1 M_Jup, P=1.9 dHD 4113 C: 35–50 M_Jup, T eff~900 K~40Crida et al. (2018)
The HD 38529 system, a G4IV star 138 light-years in Orion, includes a Jovian planet HD 38529 b (m sin i ≈ 1.2 M_Jup, P ≈ 14.3 days, a ≈ 0.13 AU) found in 2002 via radial velocity. Its brown dwarf companion, HD 38529 c (mass ≈ 37 M_Jup, spectral type L1, P ≈ 5.8 years, a ≈ 3.7 AU), was confirmed through Hipparcos astrometry in 2009, resolving its true mass beyond the planetary regime. This system's hierarchical architecture demonstrates long-term stability despite the brown dwarf's influence on the planet's eccentricity. Another well-studied case is HD 4113, a G5V star 156 light-years in Eridanus, with a close-in giant planet HD 4113 A b (m sin i ≈ 1.1 M_Jup, P ≈ 1.9 days, a ≈ 0.02 AU) detected in 2009. The brown dwarf HD 4113 C (mass 35–50 M_Jup, T_eff ≈ 900 K, separation ≈ 40 AU) was directly imaged in 2017 using VLT/SPHERE, revealing an ultracool atmosphere and confirming its substellar nature. Orbital analysis indicates the brown dwarf orbits the planet-hosting primary, forming a stable quadruple system with a distant M-dwarf companion. These systems, detected primarily through surveys like CORALIE and HARPS, underscore the diversity of substellar companions and their role in shaping planetary architectures. Recent Gaia data has identified additional candidates, revealing wide-orbit brown dwarfs around ~4% of exoplanet hosts, though confirmation requires multi-epoch imaging.

Disputed or Candidate Cases

In exoplanet astronomy, disputed cases often arise from radial velocity (RV) detections where stellar activity, such as starspots or long-term magnetic cycles, can mimic planetary signals, leading to false positives in multiplanetary system claims. A prominent example is the Gliese 581 system, an M-dwarf star hosting a compact planetary architecture approximately 20 light-years from Earth. Initial RV observations from 2005 to 2010 suggested up to six planets, including potentially habitable ones like Gliese 581d and 581g in or near the habitable zone. However, subsequent analyses revealed that signals for planets d and g were artifacts of the star's activity, with no significant evidence remaining after modeling red noise and stellar rotation effects. A 2014 study using HARPS and HIRES data explicitly attributed these signals to starspot-induced variations, reducing the confirmed count to three inner planets (b, c, and e). More recent observations have further refined this assessment. In 2024, a comprehensive reanalysis incorporating new CARMENES RV data alongside archival HARPS and HIRES measurements confirmed planets b (minimum mass ≈16 M⊕, period ≈5.37 days), c (≈5.6 M⊕, ≈12.92 days), and e (≈1.94 M⊕, ≈3.15 days), while finding no detectable signal for planet d or the outer candidate f. This leaves Gliese 581 as a verified three-planet system, highlighting how iterative RV modeling and activity mitigation can resolve disputes in closely packed configurations. The case underscores the challenges of detecting low-mass planets around active M dwarfs, where signal-to-noise ratios are low and correlations between planetary periods and stellar rotation harmonics can lead to overinterpretation. Candidate multiplanetary systems, distinct from fully disputed ones, primarily emerge from transit photometry surveys like NASA's Kepler, K2, and TESS missions, which identify multiple periodic dips in stellar brightness suggestive of co-orbiting planets but require independent validation (e.g., via RV or imaging) for confirmation. As of November 2025, the NASA Exoplanet Archive catalogs 1,979 unconfirmed Kepler candidates, 976 K2 candidates, and 4,697 TESS candidates (TOIs), with a significant fraction occurring in multi-planet configurations—estimated at over 40% of Kepler's total candidates based on multiplicity statistics. For instance, systems like KOI-500 and KOI-730 feature multiple transit candidates with periods indicating compact architectures similar to confirmed multiplanet setups, but lack follow-up confirmation due to faint host stars or observational biases favoring single transits. TESS, operational since 2018, has amplified this pool, detecting over 7,700 planet candidates by late 2025, including dozens of multi-planet systems like TOI-561 (four confirmed planets plus one outer candidate), where empirical models derived from Kepler data predict additional undetected members but await RV validation to rule out eclipsing binaries or instrumental artifacts. These candidates are prioritized for follow-up by ground-based telescopes, as multiplicity boosts validation probabilities through statistical arguments like those in the "validation by multiplicity" technique, yet many remain unconfirmed due to resource constraints. Overall, such cases represent the frontier of multiplanetary exploration, where ~20-30% of transit candidates in multi-systems may ultimately be validated, informing models of system architectures while cautioning against premature habitability assessments.

Notable Configurations and Implications

Resonant and Architecturally Ordered Systems

Resonant multiplanetary systems feature planets whose orbital periods are locked in specific integer ratios, such as 2:1 or 3:2, leading to gravitational interactions that stabilize their configurations over long timescales. These resonances often arise from convergent orbital migration during the protoplanetary disk phase, where planets migrate inward or outward and capture each other in mean-motion resonances. First-order resonances (e.g., p+1:p) are the most common, as they provide the strongest dynamical coupling, and chains of such resonances can extend across multiple planets. Observations from transit surveys like Kepler and TESS have identified numerous such systems, with statistical analyses showing peaks in period ratios near 3:2 and 2:1 among adjacent planet pairs in multiplanetary setups. A prominent example is the TRAPPIST-1 system, an ultracool M-dwarf hosting seven Earth-sized planets in a compact resonant chain spanning orbital periods from 1.5 to 12.4 days. The planets form a near-Laplace resonance configuration, with successive pairs in ratios like 24:15, 15:9, 9:6, 6:4, 4:3, and 3:2, ensuring dynamical stability despite their close spacing. This chain likely survived disk dissipation due to tidal damping, as simulations indicate that without such mechanisms, the system would destabilize. Transit-timing variations (TTVs) confirm the resonant librations, with amplitudes indicating librational periods of decades to centuries. Another striking case is HD 110067, a Sun-like star 100 light-years away with six sub-Neptune planets (radii 1.4–2.9 Earth radii) in a pure resonant chain: successive period ratios close to 3:2, 3:2, 3:2, 4:3, and 4:3, forming a chain where orbital periods scale as approximately 1 : 1.5 : 2.25 : 3.375 : 4.5 : 6. Discovered via TESS and confirmed with and ground-based photometry, the system's brightness (V=8.3) enables precise TTV modeling, revealing libration periods from 14 to 300 years and constraining masses to 5–13 Earth masses. This sextuplet represents one of the longest confirmed resonance chains, highlighting how such architectures preserve formation histories. Architecturally ordered systems exhibit monotonic trends in planetary properties, such as radius or mass, with increasing orbital distance, contrasting with the more common "similar" architectures where planets have uniform sizes (e.g., the "peas-in-a-pod" pattern). These ordered configurations are rare, comprising about 1–2% of observed multiplanetary systems, and are classified as "ordered" when radii strictly increase or decrease outward, often linked to disk-driven migration that sorts planets by size. Anti-ordered systems, where larger planets orbit interior to smaller ones, are even scarcer and may result from inward migration of giants followed by outward scattering of smaller bodies; no confirmed examples have been observed. Kepler data reveal that ordered systems tend to be more compact, with period ratios peaking just beyond resonances, suggesting resonant trapping followed by gentle divergence. The Kepler-51 system exemplifies outward-ordered architecture, with four low-density "super-puff" planets (radii ~6–30 Earth radii) showing increasing density and decreasing scale height outward, interpreted as vapor-rich envelopes compressed by irradiation gradients (as of 2024). These ordered systems provide key tests for formation theories, as N-body simulations reproduce them via pebble accretion and migration but predict their scarcity due to frequent disruptions. A recent example is the TOI-1117 system, discovered in 2024, featuring three sub-Neptune planets where one resides in both the Neptunian Desert and Radius Valley, with resonant configurations illustrating diverse architectures near stability boundaries.

Implications for Planet Formation

Observations of multiplanetary systems, particularly those revealed by the Kepler mission, have profoundly shaped our understanding of planet formation by highlighting compact architectures and resonant configurations that differ markedly from the Solar System. These systems often feature multiple low-mass planets, typically Earth- to Neptune-sized, orbiting in close proximity with period ratios near mean-motion resonances, suggesting formation processes that favor efficient accretion and dynamical sculpting within protoplanetary disks. Such architectures challenge traditional Solar System-centric models, emphasizing the role of diverse pathways like core accretion and pebble accretion in producing stable, multiplanet outcomes. A key implication arises from the prevalence of "peas-in-a-pod" patterns, where planets within a system exhibit uniform sizes, masses, and orbital spacings, contrasting with inter-system diversity. This uniformity points to in-situ formation via core accretion, where planets grow from planetesimals in a dissipating disk without extensive radial migration, as evidenced by statistical measures of orbital spacing (S_s > 30) and mass concentration (S_c < 300) in observed Kepler systems. In contrast, systems with tighter spacings (S_s < 30) and higher mass concentrations indicate migration-dominated histories, where convergent orbital migration leads to resonant trapping and architectural ordering. accretion models further explain rapid growth of these cores at larger disk radii, enabling the formation of super-Earths and mini-Neptunes before disk dispersal. Resonant chains in multiplanetary systems, such as those in TRAPPIST-1 or Kepler-223, imply that planet formation involves dynamical interactions that stabilize orbits post-formation, often through disk-driven migration (Type I and II) that converges planets into resonances. These configurations constrain disk instability models, which are less favored for inner systems due to the scarcity of massive giants in compact setups, instead supporting hybrid scenarios where early giant planet formation influences outer disk dynamics. However, the observed diversity—ranging from dynamically cold, coplanar systems to those with moderate eccentricities—underscores gaps in current theories, particularly regarding atmospheric retention and volatile delivery, prompting refinements to incorporate variable disk conditions and metallicity effects. Overall, these systems serve as "fossils" of formation, revealing that planet assembly is more efficient and versatile than previously thought, with implications for habitability in resonant, stable architectures.

References

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