Smallest Exoplanet Records

Smallest Planet Record

• (Antiquity) Mercury - Home system of Earth, the only confirmed habitable planet. Also has three other terrestrials, two Jovians, two Neptunians, several rocky and icy Dwarf Planets, a asteroid belt, a kuiper belt, and an Oort cloud.
• (1801) Ceres
• (1802) Pallas
• (1804) Juno
• (1845) Mercury
• (1930) Pluto
• (2006) PSR B1257+12 A - The first extrasolar system confirmed and one of the only planetary systems known around a pulsar. Has three rocky planets that orbit closer than Venus. The innermost has a Moon-like mass, while the next two out are Super Earths. May also have an outer "comet" sized body, the first sub-planetary object detected and possibly a representative of a mini "kuiper belt" at asteroid belt like distance.

Smallest Exoplanet Record

• (1991) PSR B1257+12 C - The first extrasolar system confirmed and one of the only planetary systems known around a pulsar. Has three rocky planets that orbit closer than Venus. The innermost has a Moon-like mass, while the next two out are Super Earths. May also have an outer "comet" sized body, the first sub-planetary object detected and possibly a representative of a mini "kuiper belt" at asteroid belt like distance.
• (1994) PSR B1257+12 A

Smallest Exoplanet Around Normal Star Record (Minimum Mass)

• (1995) 51 Pegasi b - The star called 51 Pegasus is now known as Helvetios. Contains the first exo-planet around a normal star discovered and the first "Hot Jupiter" found, which is nicknamed "Bellerophon", and now called Dimidium. Star is about 50 ly located in the square of Pegasus, a G5 star somewhat larger and more massive than the Sun. The planet's discovery was incompatible with planetary system formation models, so they were tweaked to allow for planetary migration. It was also initially thought to be an anomaly or the stripped down core of a brown dwarf. Found to have supersonic winds that caused the eternal night-side hemisphere to be as hot as the day-side one. During its 20th anniversary, this planet became the first one's whose reflected visible light was detected. The technique involved looking at a star's visible spectrum, and then detecting a faint reflection of this spectra. Its actual mass (0.46 MJ) and inclination (9deg) were obtained as a result. The planet seems to have a larger radius and bright surface, rather typical for hot jupiters. One of the first 20 exoplanet systems allowed to be given common names by the IAU. The star's name is Latin for a Celtic tribe that lived in Switzerland (the place where its planet was discovered) during the middle ages. The planet's name is Latin for "half" due to the fact its minimum mass is half as massive as Jupiter's.
• (2000) 79 Ceti b - A yellow subgiant star around which the smaller of the first 2 Saturnians discovered (HD 46375 b was the other one) is in a Mercury-like orbit.
• (2002) HD 49674 b - Contains the first planet found to have significantly less mass than Saturn.
• (2004) Mu Arae d - Cervantes (Mu Arae) is a 6th magnitude Sunlike star close to becoming a Sub-Giant located 50 ly with four known planets. At first believed to be a system dominated by orbit crossing eccentric Super Jupiters. Instead, three Jovians orbit in roughly circular orbits at Earth-like (Rocinante, d), Mars-like (Quixote, b, in habitable zone), and Jupiter-like (Sancho, e) distances in addition to an inner (Dulcinea, c) Hot Neptune. Planet c was one of three Hot Neptunes or Hot Super Earths discovered around the same time. It was the first one announced, but it was still under scientific review at the time, so there remains controversy on what the actual first planet discovered of this class is. Initially thought to likely to be rocky because it had 2 known neighboring gas giants which may have stunted its growth. The characteristics of the planets in this system changed greatly as new planets were discovered, and included a re-ordering of their designations. Initially, the first planet b was thought to be highly eccentric. An outer planet was then detected, at the time dubbed "c" (though a full period hadn't yet been observed), and was thought to have an extremely high eccentricity so that the orbits of the two planets would cross. An innermost third planet then dubbed "d" was then detected. A new fit for the data then emerged, and it was found that the outermost planet was actually much less eccentric, and that there was a planet interior to planet b with almost half its period. The eccentricity of b was also reduced so that no planet criss-crossed another's anymore. It was decided to redesignate the planets in order of characterizations instead of by discovery, so the innermost Neptunian planet was re-dubbed "c" and the planets just interior and exterior to planet "b" were re-dubbed "d" and "e". The system became the second known 4-planet system. The innermost two Jovians are close enough so that they're unstable over short periods of time. If they were actually in 1:2 resonance, which almost fits the data, they would be much more stable. One of the first 20 exoplanet systems allowed to be given common names by the IAU. Star is named after the author of Il Ingenioso Hildalgo Don Quixote de la Mancha and the planets after its characters, Quijote (main character), Dulcinea (love interest), Rocinante (horse), and Sancho (squire).
• (2005) Gliese 876 d - Ross 780 is also known as Gl 876 and the flare star IL Aquarii. Very nearby quadruple planet system and the first Red Dwarf found to have planets. The innermost planet (d, Hot Superterran, rocky-water) was the first found rocky planet around a normal star (the first true Super-Earth, at epistellar distances). The outer three planets c (Warm Saturnian), b (Warm Jovian), and e (Cold Neptunian) are in 1:2:4 (30d/60d/120d) resonance (the exoplanet resonance and first triple-resonant planets discovered). The outermost planet has a Mercury-like orbit. Planet b is second discovered by ELODIE after 51 Peg b and the second to have its mass exactly measured and the first to have done so by astrometry.
• (2005) OGLE-2005-BLG-390L b - Has first discovered Icy Super Earth, which was detected via Micro-lensing tens of thousands of light years away and was the smallest known exoplanet around a normal star at the time.
• (2007) Gliese 581 c - BD-11°3759 is better known as Gliese 581. Small nearby Red Dwarf with six planets in tight circular orbits. Several planets were announced in the habitable zone, but have since been retracted due to being due to sunspots rotating in view during it's 130 day rotation. E is the smallest known dopplar-detected exoplanet and a Super Mercury, b is a hot Neptunian, c is a super-Venus and the first detected in the HZ (initially heralded as habitable, but later thought too hot due to the greenhouse effect). G (1/4 stellar rotation) was the most controversial heralded as the first habitable Super-Earth and "Eyeball Earth", but was disproven. D (1/2 stellar rotation) was later thought to be an even more promising planet for life as it was big enough for a decent greenhouse effect even though it was at the outer edge of the habitable zone, was later thought to also not exist, but then its existence was re-affirmed. F was thought to be a cold super-Earth, but also disproven. The star is not very active. A massive Kuiper Belt was found, which may have been allowed to exist because the system lacks a Jovian class planet. A further out Neptunian may be responsible for the cometary collisions that produced the debris.
• (2008) Gliese 436 c - AC+27°28217 is best known as Gliese 436. The second known red dwarf planetary system. Contains one of the first Neptunians discovered and a few potential planets. The star is about half the sun's mass. It is over 11 Billion years old and may be a part of the old disk of the Milky Way. Planet b temporarily later found to be the smallest exoplanet (about Uranus' diameter, though over 50% its mass) known to transit its host star and is currently the nearest (33 ly). Its temperature (712K) was measured to be higher than what it would be purely from radiation (520K), perhaps due to a greenhouse effect, somewhat higher than Venus. It was originally thought to have a layer of "hot ice", water solidified due to high pressures. It turned out that it was larger than thought and hot ice was not needed. It could still be a rocky super-Earth. It was later found to have a remarkably low levels of Methane and high levels of Carbon Monoxide for its 800K temperature. Possible explanations include Methane being changed into hydrocarbon polymers due to its star's ultraviolet radiation, CO being drafted upwards with winds, or observational defects. Later, due to lack of detection of chemical signatures through the backlit atmosphere, it was concluded that high altitude clouds, perhaps made of potassium chloride or zink sulphide dust, were blocking the detection. This could be the first detection of clouds of a Neptunian. An alternate theory is that the atmosphere is filled with heavy compounds, such as water, carbond dioxide, which would compress the atmosphere and make it difficult to detect. After detection of a huge comet-like tail of Hydrogen trailing and wrapping around its orbit led to the most recent theory that it lost its Hydrogen to uv radiation and was left with a Helium dominated atmosphere with plenty of CO instead of CH4. It's significant eccentricity suggests a possible neighboring planet. Planet c was announced to be the smallest known exoplanet (1.5 Earth's diameter), but was later retracted because variations in transit timing of the first planet did not occur and the proposed orbit would be unstable. It is still thought that a second planet of some kind is possible in the system. Candidate UCF-1.01 was detected by a student in the UCF's astronomy department using the Spitzer Space Telescope. It is about 2/3 Earth's diameter (smaller than all but one confirmed exoplanet), orbits around its star in 1.5 days, and at 1000F may be a lava world without an atmosphere. UCF-1.02 also may exist. Both are thought to be about 1/3 as massive as the Earth, but are too small to get their mass measured and thus too small to be confirmed with present technology.
• (2008) MOA-2007-BLG-192L b - A very dim Red Dwarf star (once thought to be a potential Brown Dwarf) around which the smallest known exoplanet around a normal star (1.4 ME, once thought to be 3.3 ME) orbits. Orbiting at Venus-like distances, the planet is likely an icy frozen super-Earth.
• (2009) Gliese 581 e - BD-11°3759 is better known as Gliese 581. Small nearby Red Dwarf with six planets in tight circular orbits. Several planets were announced in the habitable zone, but have since been retracted due to being due to sunspots rotating in view during it's 130 day rotation. E is the smallest known dopplar-detected exoplanet and a Super Mercury, b is a hot Neptunian, c is a super-Venus and the first detected in the HZ (initially heralded as habitable, but later thought too hot due to the greenhouse effect). G (1/4 stellar rotation) was the most controversial heralded as the first habitable Super-Earth and "Eyeball Earth", but was disproven. D (1/2 stellar rotation) was later thought to be an even more promising planet for life as it was big enough for a decent greenhouse effect even though it was at the outer edge of the habitable zone, was later thought to also not exist, but then its existence was re-affirmed. F was thought to be a cold super-Earth, but also disproven. The star is not very active. A massive Kuiper Belt was found, which may have been allowed to exist because the system lacks a Jovian class planet. A further out Neptunian may be responsible for the cometary collisions that produced the debris.

Smallest Exoplanet (Measured Radius)

• Kepler-37 System (0.3 RE, Feb 2012) - Kepler-37 is also known as KOI-245 and UGA-1785, a nickname honoring the University of Georgia and officially authorized by NASA. This was the second official nickname sponsored by NASA and the first named after a University. It was named so because the light that is visible right now came from the star in 1801, the same year the Franklin College was founded and classes began at UGA. The innermost planet b was initially the smallest yet detected by Kepler (slightly larger than the Moon) and orbits once every 13 days. A planet this small was only detectible because of the extraordinarily stability of the parent star's (25% smaller than the Sun) light output. The second planet c is 35% further out and 75% the size of the Earth. The outermost planet is twice the Earth's size and 0.2 AU. The three planets are close to 5:8:15 mean motion resonance. The star is similar to the Sun and the smallest star measured by astroseismology (3/4 the Sun).
• Kepler-42 System (0.57 RE, Jan 2012) - Nearby Red Dwarf Kepler star Kepler-42 is also known as KOI-961. Has three transiting planets in torch orbits smaller than the Earth, including the smallest yet measured at the time of discovery. Planets are is c (~1.9 ME, 0.72 RE), b (~2.8 ME, 0.78 RE), and d (~0.95 ME, 0.57 RE, Earth-massed but Mars-sized). The planets have not been detected with dopplar spectrometry yet, so the masses and densities aren't known. Transits were detected independently and it is very unlikely the planets are not there. Nicknamed "Planets of the Apps" after a British amateur astronomer who alerted astronomers of the system's significance. The star was compared to Barnard's Star, in that they are both nearby and old. Comparison to this well known star assisted in the system's study. The system is comparable in scope to the Jovian system, more so than any other system. Outer Space Message Center lists this as one of the targets laser messages can get sent to.
• Kepler-20 System (0.87 RE, Dec 2011) - An unusual 5 planet system (b-e-c-f-d) discovered by the Kepler spacecraft containing 3 Neptune-sized objects (b, c, d) and 2 Earth-sized objects (e, f), which are in alternating distances from the star, with the outermost one orbiting only in 78 days. Planet f has nearly the identical radius as Earth (1.03 RE), while planet e is the first sub-Earth planet (0.87 RE) discovered around a normal star, and were the smallest discovered yet at the time.
• Kepler-10 System (1.4 RE, May 2011) - An old sun-like star with a hot rocky Super-Earth (b) and a mega-Earth (c) in a Mercury like orbit. B is an airless Super-Earth covered in an ocean of magma with a high density, likely metallic. Its high density means its almost entirely composed of Silicate and metals. Had smallest measured diameter of any exoplanet (40% more than Earth, 4.5 Earth's mass, and nicknamed Vulcan by scientists) and is the first rocky exoplanet found by Kepler. Its daytime temperature is 1,500C, well over the melting point of Silicate and nearly that of Iron. The planet is glowing hot and lava pieces fly away from it like a cometary tail. Planet is similar to Corot-7b, but is around a more quiet star, making measurements more reliable, and thus this planet is the first certainly rocky planet discovered. Has circular orbit, so not likely a super-Io like that planet, instead considered a super-Mercury. Planet c was the first mega-Earth discovered and needed to be confirmed with the Spitzer telescope. Its diameter is 2.3 that of Earth and a mass of 17 that of Earth. It was thought rocky planets could get that big without absorbing enough gasses to make them gas giants. It is thought the planet never had an atmosphere because it is large enough to have kept it.
• CoRoT-7 System (0.15 RJ, 2009) - A sunlike star about 500 light years away with two Hot Super Earths (and possibly a third), including the first detected transiting Super-Earth. It a diameter about twice that of the Earth. First exoplanet with evidence of a solid surface and does not possess a thick atmosphere. Because its star is active, its mass is somewhat uncertain (2.3 to 8.5 ME), which makes it unclear if the planet actually has a solid surface. Also the closest exoplanet to its star known and has the smallest orbit period (0.85 Earth Days). Likely the first Super-Io discovered (due to slight eccentricity) and the first gas giant remnant core found. Has temperature of 1000-1500C. Planet c is a larger Neptunian orbiting further away and does not transit.
• Gliese 436 System (0.438 RJ, 2007) - AC+27°28217 is best known as Gliese 436. The second known red dwarf planetary system. Contains one of the first Neptunians discovered and a few potential planets. The star is about half the sun's mass. It is over 11 Billion years old and may be a part of the old disk of the Milky Way. Planet b temporarily later found to be the smallest exoplanet (about Uranus' diameter, though over 50% its mass) known to transit its host star and is currently the nearest (33 ly). Its temperature (712K) was measured to be higher than what it would be purely from radiation (520K), perhaps due to a greenhouse effect, somewhat higher than Venus. It was originally thought to have a layer of "hot ice", water solidified due to high pressures. It turned out that it was larger than thought and hot ice was not needed. It could still be a rocky super-Earth. It was later found to have a remarkably low levels of Methane and high levels of Carbon Monoxide for its 800K temperature. Possible explanations include Methane being changed into hydrocarbon polymers due to its star's ultraviolet radiation, CO being drafted upwards with winds, or observational defects. Later, due to lack of detection of chemical signatures through the backlit atmosphere, it was concluded that high altitude clouds, perhaps made of potassium chloride or zink sulphide dust, were blocking the detection. This could be the first detection of clouds of a Neptunian. An alternate theory is that the atmosphere is filled with heavy compounds, such as water, carbond dioxide, which would compress the atmosphere and make it difficult to detect. After detection of a huge comet-like tail of Hydrogen trailing and wrapping around its orbit led to the most recent theory that it lost its Hydrogen to uv radiation and was left with a Helium dominated atmosphere with plenty of CO instead of CH4. It's significant eccentricity suggests a possible neighboring planet. Planet c was announced to be the smallest known exoplanet (1.5 Earth's diameter), but was later retracted because variations in transit timing of the first planet did not occur and the proposed orbit would be unstable. It is still thought that a second planet of some kind is possible in the system. Candidate UCF-1.01 was detected by a student in the UCF's astronomy department using the Spitzer Space Telescope. It is about 2/3 Earth's diameter (smaller than all but one confirmed exoplanet), orbits around its star in 1.5 days, and at 1000F may be a lava world without an atmosphere. UCF-1.02 also may exist. Both are thought to be about 1/3 as massive as the Earth, but are too small to get their mass measured and thus too small to be confirmed with present technology.
• HD 149026 System (0.654 RJ, 2005) - Ogma (HD 149026) is a yellow sub-giant star with the first known Saturn mass transiting planet, Smertrios. Also the first planet found with a dense core, leading credence to the core-accretion theory. Sometimes called a Super-Neptune, though it is not known if its core is rocky or icy. Also the first TEP discovered smaller than Jupiter. It was revealed to be as black as coal, twice as hot as any other known exoplanet, and hotter than some stars. One of the first 20 exoplanet systems allowed to be given common names by the IAU. The star is named after a Celtic god of eloquence, writing, and great physical strength, while the planet was named after a Gallic deity of war.
• HD 80606 System (1.029 RJ, 2003) - Multiple star system (also known as Struve 1341) with a planet, which had a higher period (111 days) than any other known transiting planet and highest eccentricty (Halley's comet-like, epistellar distances to almost Earth-like distance) prior to the release of Kepler data. It is the nearest transiting Super Jupiter (4 MJ, radius slightly less than 1 RJ, 190ly). Its length of day is 36 hours. Discovered in 2001, but found to transit in 2009. Planet is the first one for which changes in weather have been observed. Potassium was detected from the high wind regions of the exosphere. In 2010 it was found to be only one of the two out of all 79 known transiting exoplanetary systems that could not support a habitable Earth-like planet, since its elongated orbit would destabilize any such planets. Planet thought to be in the process of becoming a Hot Jupiter. Observations suggested that energy transferred during closest approach to star would take 10 Billion Years to cause the orbit to circularize, meaning this tidal migration method may not be the preferred one to form hot jupiters.
• OGLE-TR-56 System (1.3 RJ, 2002) - Contains first planet discovered by transit and later confirmed by Dopplar Spectroscopy (rather than the other way around). The first OGLE planet confirmed with the Dopplar method. It is 6000 ly away, 10 times as far as any previous known planet, in a different arm of the galaxy. Also the first Very Hot Jupiter and the first non-inflated Hot Jupiter discovered. It may meet its doom in less than a million years. Planet has one of the first two ground-detected atmospheres. Has an atmosphere hotter than any other measured so far. Unlike other hot Jupiters observed, it is way too hot for clouds of silicon or iron to form which would keep it dark.

• HD 209458 System (1.32 RJ, 1999) - Has first discovered transiting planet which was nicknamed Osiris due to the (first detected) comet-like tail detected and the first exoplanet around a normal star to have its mass directly measured. Also the first Inflated Hot Jupiter found. The planet may be losing its outer atmosphere, or magnetism may prevent the ions from escaping. They detected water in its atmosphere (they had failed earlier), the first time this has been done for any exoplanet. 2nd Exoplanet with detected organic compounds; like HD 189733b, it has water and carbon dioxide, but it has a lot more Methane. Was one of 2 planets to have light directly taken and thus their temperatures read (over 1000K). Tracking carbon molecules with dopplar spectrometry caused it to be the first exoplanet detected to have winds, which are raging at 5,000 to 10,000 km/h. This is believed to cause hotspots to appear at terminators rather than at the star-ward facing point. Had one of the strongest water detection of the 5 exoplanets contrasted by Hubble in 2013, though still less intense than expected, probably due to dust clouds or a haze blocking its detection.

Smallest in Habitable Zone

• Kepler-22 System - Contains the smallest planet in the habitable zone around a star at the time of its discovery by Kepler. The first around a sun-like star at Earth-like distances that is not probably tidally locked. The first potentially habitable planet confirmed (transits confirmed on other telescopes). Orbits around a sun-like star about every 290 days. It is about 2.4 times the radius of Earth and most likely gaseous. Its mass is difficult to measure and may be beyond the ability of modern telescopes (Keck will give it a try), so it has not been confirmed to be rocky yet (some planets the same size are either). A new technique determining mass from atmospheric pressure may one day help nail down its mass. It was the first of 54 habitable zone planet candidates to be independently confirmed. Depicted in art as blue with green clouds, the Scientific Exoplanets Renderer did not compute that it was habitable though. Its surface temperature is 76F, similar to a spring day on Earth. Searches for a potentially habitable moon, which it was predicted to be a good candidate for, have not found anything.
• Gliese 370 System - Also known as HD 85512, contains the second of three confirmed potentially habitable planet as of 2011. One of over 50 exoplanets and 16 Super-Earths discovered by HARPS at the ESO using the radial velocity method. It is about 3.6 Earth Masses at the inner edge of the habitable zone. The smallest exoplanet yet found potentially in the habitable zone when discovered. It could be between 85 to 120F. It could be habitable if it exhibited more than 50% cloud cover. It was rendered by the Scientific Exoplanet Renderer.

Smallest Visually Detected Planet

• Gliese 504 System - Young (160 MYO) Sun-like star 57 ly away, visible to the naked eye in Virgo and put on star charts since 1598. Contains the smallest visually detected planet. Its about four times as massive as Jupiter and the same size, which has dubbed it as a second Jupiter. It is rather blue, with a dark magenta hugh, which is the second exoplanet whose color has been directly detected. Orbits beyond Neptune-like distances, challenging formation theories, since there's not enough material at this distance.

Other "Smallests"

• HAT-P-12 b (2009, Smallest Jovian) Contains a Saturn-sized transiting planet around a metal poor K star. It broke Saturn's record for the least massive Hydrogen/Helium dominated gas giant known to date. Being so hot, the planet is almost as large as Jupiter. Transit was detected by an amateur astronomer.
• Kepler-47 System (Smallest transiting circumbinary planet) - The first multiplanet circumbinary star system found. Contains a yellow and red dwarf. The inner planet has 3 times Earth's radius and a period of 49 days. This planet is thought to have a thick blanket of methane haze around it. It is the smallest known transiting circumbinary planet. The outer planet is the furthest known transiting exoplanet with a period of 303 days. It is a Uranus-sized planet in the habitable zone. The stars go around each other once every week, causing the planet to experience several percentages of difference in temperature. Assuming a 24 hour day, they would rise and set about 30 minutes after each other, and can also be seen regularly eclipsing each other. A moon around this planet could be habitable. This system challenges planetary system formation theories. Planet c, unlike other known circumbinary planets, orbits far enough out to not need to have formed out further than it is today.
• Kepler-78 System (Sep 2013, smallest with both mass and radius measured) - System 400 ly awaycontaining a Hot Terran planet most similar Earth's mass (1.86 ME), diameter (1.16 RE), density (5.3 vs Earth's 5.5) and composition in 2013. This is the smallest planet whose size and mass have been measured, and is likely made of mostly rock and iron. Its star is 73% as large as the sun, and it orbits every 8.5 hours, has a temperature of more than 2000C than Earth, and likely has a molten surface. It has the tightest orbit confirmed. It will eventually be broken up by its star and vaporize. A mystery is how it got there, since if it had formed where it is now, it would now be inside the star, which used to be larger. A bright enough planet to be observed by the largest earth-based telescopes. The surface is so hot that shines brightly in visible light, which can be isolated from the star.
• Fomalhaut System (possibly smallest visually detected, size unknown) - Fomalhaut is also known as Piscis Austrini, 24 Piscis Austrini, Gl 881, HD 216956, and HR 8728. A triple star, the second brightest star known to have exoplanets. Star A is a white main sequence star about twice the Sun's mass and somewhat less than twice its radius. It was originally thought to be about 200 million years old, but now thought to be 400 MYO, and will turn into a giant in about a billion years. Its dust disk is observed in unprecedented detail. It appears reminiscent of the "Eye of Sauron" from the Lord of the Rings films. A planet suspected of causing a sharp gap in the ring was suspected and imaged, becoming the first visually detected and the first planet since Neptune to be predicted prior to its discovery. The planet, Dagon, orbits about 115 AU and is between Neptune and 3x Jupiter's mass in an eccentric orbit. Planet b was shown to deviate slightly from its predicted path, stirring up some controversy about the planets' existence. The Hubble instrument that detected it is damaged and will not be fixed, making it unobservable for a time. Later analysis of old Hubble data confirmed its existence. Material surrounding the planet has been imaged, rather than the planet itself, which its discoverers admit takes it off the directly imaged list. The planet is hurdling outward from the star in a highly elongated path and will encounter the inner edge of the outer belt in 2032, where icy debris will smash into its atmosphere (unless its orbit is highly inclined). No heat has been detected from the planet, which suggests it is sub-Jovian in mass and could be as small as Pluto, though this could be explained by dissipation from surrounding dust. Evidence for another planet "slicing" through the dust disk was also found, and it may have been responsible for planet b's elliptical orbit. The shape of the ring was put into focus by ALMA, 140 AU out, 16 AU wide, and 1/7th AU thick, placing limits on proposed shepherding exoplanets and showing them to be quite small (a couple times larger than Mars), perhaps why they weren't detected visually. Mapping by ALMA was completed later on and shows the first "apocenter glow", where dust particles clump around slower moving and further out parts of their elliptical orbit. Some proposed inner planets via effects of debris disk could be better interpreted as gas produced effects. The ring is believed to be continuously replenished by cometary collisions occurring every day. An estimated 260 Billion to 83 Trillion comets could exist in it, equivalent to what is in the Sun's Oort Cloud. Star B, an orange dwarf 0.91 ly away has no known disk. Star C, a recently identified Red Dwarf member of the system, located extremely far from the primary (2.5 ly), was also found to have its own disk. Previous interactions may have tilted Star A's disk. The star is a part of the Castor Moving Group. One of the first 20 exoplanet systems allowed to be given common names by the IAU. The planet is named after a half fish Semitic god.