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Exoplanetary Scratchpad

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Not Disputed[]

  • Fomalhaut System - 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.
  • HR 8799 System - Hot young star system 300 ly away which is the only imaged and wide multiplanetary system. The 30 MY old star is the only known Gamma Doradus variable that is also a Vega-like star. The innermost is e (14.5 AU, 10 MJ), followed by d (24 AU, 10 MJ), c (38 AU, 10 MJ), and b (68 AU, 7 MJ). Inside the inner planet's orbit is an asteroid belt, while outside of the outer planet is a cometary belt (including a clump at 1:2 resonance with the outermost planet), while further yet is a huge halo extending to 2000 AU. The outer three are planets are 2-2.5 times as far as Saturn, Uranus, and Neptune are respectively, but receive similar radiation. The large planets would likely pull the system apart, leading scientists to believe the inner three planets are probably locked in a 1:2:4 orbital resonance in order to maintain stability. An inner planet is at Saturn-to-Uranus-like distances and challenges planetary formation models. Fomalhaut is the only other system where interaction between planets and dust belts can be observed. They are near the upper limits of mass to be classified as planets and could be Brown Dwarves. Upper mass limits are determined by system stability models. All three planets were later found in archived Hubble images. The middle planet became the first to have its spectrum directly measured. The spectrum confused scientists and didn't fit current formation theories. They contain carbon monoxide and are depleted in methane, which suggests they were formed in part by absorbing comets in the system. The outermost planet b has unusually thick dust clouds. There is possibly a fifth undetected planet in an inner resonant orbit.
  • Beta Pictoris System - Young massive star with the first discovered circumstellar disk and the source of most interstellar meteorites in the Solar System. Comet crystals were found to be similar composition as those in Solar System. The first exo-comet was discovered in this system in 1983 and is the only star known with a detected comet known to also have a planet. Hundreds of comets detected by transit, of which on average of 6 transits occur in a 30 minute spetra, have been placed into two groups. One family (Population D for "deep" absorption lines) were older comets depleted of their volatiles and trapped in mean motion resonance with planet b or another undiscovered one. The other is fresher (Population S for "shallow"), emit more dust, follow similar orbits, and may have been formed after the breakup of a larger object. Contains the youngest known exo-planet, which shows that Jupiter-like planets can form much quicker than previously believed. It is the closest-in exoplanet photographed and is at 8 AU and 7-11 Jupiter Masses and orbits in 20 years. This planet was first hinted at by studying dust disks in 2003 and first photographed in 2003, but it was not confirmed and was lost. It was imaged again in 2008, and became the first imaged exoplanet confirmed to move around its star in 2010. It has an effective temperature of 1,100 to 1,700C, showing that it is still warm and has retained much of its heat from its formation. Evidence of a planetary transit in 1981 was found in record. It was originally thought that a second planet must have caused a tilt in one of the disks, but now it known that the first planet is. Models show that it could create waves and spirals in the disk. Some data suggests the planet is unusually wide, perhaps evidence of a ring system around it. The planet is traveling through a relatively dust-free gap in the debris disk, and thought to be clearing it. The planet is losing momentum as it travels through the debris disk. A large belt of carbon monoxide 50-160 AU concentrated at 85 AU has been observed, possibly caused by collision of comets. A Saturn sized planet interior to the belt that is not currently detectable due to being edge on in the disk could be shepherding it. It is possible that diamond-planets are forming in the disk. A cubesat could target this star in search of a second planet using the transit method since the system is edge-on. Principle member of the Beta Pictoris Moving Group.
  • Kappa Andromedae System - The most massive known star to have a planet around it. It has a large planet (13 Jupiter masses, possibly a Brown Dwarf) which was discovered visually through the infrared by SEEDS. It orbits twice as far as Neptune is from the Sun and is 2,600C. The star is a naked eyes star, is 170 light years away, and is about 30 Million years old.
  • HD 95086 System - A young star 10-17 MY old and 300 ly away a little more massive than the Sun which has a dust disk. It also has an imaged planet twice as far as Neptune and 4-5 times as massive as Jupiter (the least massive exoplanet imaged so far whose mass is reasonably well known). It has been determined to change position and may have formed where it is, or was flung out due to gravitation interactions. The planet was imaged by the same team that imaged the planet around brown dwarf 2M1207. The planet is 700C, cool enough for water vapor or methane to exist in its atmosphere, which may be detected later. It appears as a blue fuzzy blob.
  • 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.
  • HD 106906 System - Young system with an extremely far flung visually detected planet. Found at 650 AU and 11 times Jupiter's mass. Furthest out known planet around a single star. It orbits further out than planet accretion theories allow for. There appear to be no other nearby planets or stars which could have flung the planet from a closer orbit. The star was found later on to be a binary star. The planet could have been further in and then expelled by one of them. The ratio of star to planet mass is 1 to 100, lower to be formed like a binary star, whose ratios are no more than 1 to 10. The planet is 13 MY old and still glowing from its formation. It was detected with a thermal infrared camera on Magellan telescope in Chili and confirmed by historical Hubble data. Star has a debris disk 50 AU wide similar to the Kuiper Belt, fat on one side and skinny on the other side. The planet is highly tilted with respect to its plane, so it must have been moved to its present location. Closer in planets were not detected. A passing star could be responsible for the lop sided belt and far out orbit of the planet.


  • GJ 758 System - Star with a giant planet or Brown Dwarf (M betw 10-40MJ) which has been directly photographed. Reguardless of its nature, it is the first and coolest substellar companion to a sunlike star ever photographed (333 C, about as hot as Mercury). It orbits at about Neptune's distance and is still in the contraction phase. A possible third companion may have been imaged, later observations should determine if it is bound to the system or merely an object in the background.
  • TMR-1 System - A binary star in the Taurus molecular cloud with a photoed object C (potentially a planet or brown dwarf) appearing to have been ejected by the system and shown pulling some dust away from the binary. This could have been the first visually detected planet, found in 1998. Later, it was said to be a background star by its discoverer. New evidence supports that this is indeed a planet, as archive photos found the star to have brightened in the past. As of 2013, its planetary status is still uncertain.


  • GQ Lupi System - A T-Tauri K-Class star that may have a massive planet with a period of about 1200 years that might be the first planet imaged.
  • 2M1207 System - A Planemo or Super Jupiter 4 times Jupiter's mass orbiting a brown dwarf 172 ly away. The planemo is possibly the first "planet" imaged and orbits 40 AU. A disk around the Brown Dwarf was known, but recently a disk around the Planemo was also detected. It is believed to be glowing hot from a recent collision with a Uranus sized planet. The planemo probably didn't form the way planets do, but rather, in the same manner as binary stars do. It is only 10 MYO and still contracting and radiating heat. Its cloud top temperature is above 2000F, making it possible rock and iron rain might form. Its rotational period is estimated to be around 11 hours, about the same as Jupiter.
  • SCR 1845 System - Template:SCR 1845 System
  • AB Pic System - Template:AB Pic System
  • White Dwarf Planetary System - An unnamed white dwarf star with a potential planet that may have been directly imaged by Hubble, which would make it the first planet imaged.
  • 1RXS J160929.1-210524 System - Contains first exoplanet (full name 1RXS J160929.1-210524) imaged around a sun-like star, photographed in 2008 and confirmed to orbit star in 2010. The planet's very large distance from the star 330 AU causes problems for planetary formation theories. Some liken it to an unbalanced binary star system where one component gobbled up the vast majority of the dust. It has about 8 times Jupiter's mass and 11 times Neptune's distance. It could be a new type of sub-stellar object between a planet and a Brown Dwarf. First exoplanet to have its spectrum taken, which revealed evidence of water, carbon monoxide, and hydrogen. Its star is young enough (5 MY) so that the planet has not had enough time to cool (1,500 C) and thus detectable.

Feature Articles[]

See 2M1207 System ("Brown Dwarf and Child"), 1RXS J160929.1-210524 System ("Far Out Planet"), HR 8799 System ("Planetary Family", "Family of Four", and "Seeing in the Future"), Fomalhaut System ("A Controversial Case"), Beta Pictoris System ("Inner Planet" and "Going Around")