| Exoplanetary Scratchpad|
Systems Within 10 Light YearsEdit
- 4.3 ly - Alpha Centauri System - Alpha Centauri is also known as Rigil Kentaurus. A is also known as HD 128620 and HR 5459, B is HD 128621 and HR 5460, and C is Proxima Centauri. It is the nearest star system to the Sun. Contains a yellow dwarf star a little bigger than the Sun and an orange star a little smaller orbiting each other orbiting each other about the distance Uranus is from the Sun (varies from Saturn like to Neptune like), as well as a distant Red Dwarf companion Proxima that may or may not be orbiting the other two.
Stellar fingerprinting suggests a high probability that a planet orbits star A, due to dearth of Iron around star. Russian astronomers announced the detection of a second planet orbiting the binary pair at 80 AU with a 100 year period, which appears to be false. The stars in the system will become markedly closer together in 2016, making observations much more difficult and one follow up failed to find it. The system is the first target for the European Cheops exoplanet space telescope.
First planet discovered is an Earth-massed rocky-iron planet with no atmosphere at epistellar distances around the orange dwarf star B found by HARPS. This is the least massive planet found around a sunlike star. The planet was informally and controversially named by Uwingu during a fund raising naming contest Albertus Alauda, after a participant's grandfather. Earthlike planets are not detectable in the habitable zone with present radial velocity methods. Technique for detection of planet is a source of doubt for some and it has yet to be independently verified. A team thought they might have detected a transit of this planet, but further observations showed the timing wasn't consistent. It is possible that a second further out (20.4 day period) Earth-sized planet is altering the transit times of the first. A cheap crowdfunded satellite devoted to studying this star could confirm the planets. The star was observed to be a good candidate to host a "super Habitable" planet, which would have 25% more gravity than the Earth, shallow seas, flatter landscape, higher atmospheric pressure, and the 6 BYO star would be stable for life longer.
Proxima, a small flare star, was discovered in 1915 by Robert Ines, who named it. Long suspected planet around Proxima found not to exist. The Pale Red Dot project is dedicated to finding a planet around Proxima using dopplar spectrometry. As Proxima passes in front of two stars (once in 2014, again in 2016), any planets within 5 AU should be detectable via microlensing using the HST. It is known that no planets of Neptune sized mass exist within 1 AU and no Jovians with periods up to 1000 days, or transiting planets exist. An Earth-like planet in the habitable zone was discovered around Proxima Centauri. In 2017, a large stellar flare erupted and bombarded the planet, making it likely that the atmosphere has been completely stripped away by events such as this and not a good candidate for life. It was thought that a lot of dust existed in the system, making it feasable that the star had a rich complement of planets, but this seems to not be the case.
- 5.8 ly - Barnard's Star System - Barnard's Star is also known as Gliese 699 and informally as Proxima Ophiuchi. Named for the astronomer E. E. Barnard, who discovered it in 1916 and was the first to measure its proper motion. Second closest star system to the Sun and the one with the highest proper motion in the sky - due to its rapid approach to the Sun. Will get as close as 3.8 ly away in 12,000 years. A red dwarf thought early on to have a planet around it found due to radial velocity method, which has been disproved. A super earth has been detected at Mercury-like distances, but beyond the frost line. Life could be possible if an additional source of heat was provided. A potential target for the 1970's Project Daedelus. The star is very ancient 11-12 Billion Years Old, and is the nearest inactive Red Dwarf Star. It may take another 40 Billion Years before it cools to become a Black Dwarf. Astronomers were surprised to discover that it was a flare star in 2003, and dubbed it V2500 Ophiuchi.
- 8.3 ly - Lalande 21185 System - Lalande 21185 is also called GJ 411 and informally Proxima Ursa Majoris. It is the fourth closest star system to the Sun at 8.3 ly. It is the third brightest red dwarf in the night sky. It has been the spectral standard star for class M2 V for a long time. It is sometimes classified as a BY Draconis type variable star and has been known to emit x-rays. Van de Kamp thought he found planets in 1951. The system has two unconfirmed planets detected via radial velocity in 1996. It is also one of the earliest planets detected that still has a good chance to exist. The planets orbit far away from their dim Red Dwarf star, which makes one planet colder than Saturn and the other colder than Neptune despite being at a Saturn-like distance. One confirmed planet is a hot super earth with a rocky surface. The star is the nearest Galactic 'Thick Disk' star (which includes about 4% of nearby stars), and moves perpendicular to the galactic plane. It will get nearest to the Sun in 19,000 years when it is 4.65 ly.
Systems Within 20 Light YearsEdit
- 10.5 ly - Epsilon Eridani System - Ran (Epsilon Eridani) is the nearest single non-red dwarf star to the Sun, also known as HD 195019, Gl 144, and HR 1084. It is a member of the Ursa Major star association and close encounters to other stars is relatively common. One of the first stars found to have a dust disk, with several potential planets suspected in the gaps early on, and later on of the earliest nearest system with confirmed planets. Has an inner asteroid belt at 3 AU, Jovian planet AEger at 3.4 AU, outer asteroid belt at 20 AU, and Kuiper Belt at 35-100 AU. A planet is proposed to be just outside the outer asteroid belt, and another just before the Kuiper belt.Because the star is very chromospherically active, doubts were cast on planet's b's existence. Hubble then confirmed its existence with astrometrics and found to be orbiting in the plane of the dust disks, which supported the theory that planets are born from dust disks and yielded a precise mass of 1.5 MJ. The planet b was originally thought to be extremely eccentric (2-10 AU), but later discovery of the inner asteroid belt suggests it is more moderately eccentric so as not to cross the belt. It could still have high eccentricity if the outer belt was being fed with material from the outer belt though. Dinosaur-killing sized impacts would be frequent on any Earth-like planets, about once every 2 million years. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation. One of the first 20 exoplanet systems allowed to be given common names by the IAU. Star is named after a Norse goddess of the seas, while the planet after her husband, god of the ocean. A common sci fi system, including the original home of Star Trek Vulcans (though this moved to 40 Eridani) and Babylon 5.
- 11.6 ly - Groombridge 34 System - Groombridge 34 is also known as Gliese 15 and HD 1326. It is a double red dwarf star. Both are flare stars, with A being dubbed GX Andromedae and B GQ Andromedae. The stars are 147 AU apart in nearly circular orbits. Ross 248 is only 1.8 light years away. Currently the closest known multi-exoplanetary system.
- 12.8 ly - Kapteyn's Star System - Kapteyn's Star is also known as VZ Pic, Gl 191, HD 33793, and Cordoba Zone 5 hours 243. Kapteyn noticed that a star was missing from a catalog until its new position was found. Has the second highest proper motion of any stars. Also informally called Proxima Pictoris. Nearby large and old Red Dwarf star system and nearest Halo object thought to be a remnant of the nearest and largest global cluster, Omega Centauri, which is 16,000 ly away and shredded by the Milky way 11.5 BYA, and born while that was still a separate galaxy. 2.5 times as old as the Sun and born when the Universe was only 2 BYO. Was within 3 light years of Epsilon Eridani 31,500 years ago. Will be on the other side of the galaxy in 100 MY. Is a sub-dwarf or main sequence star. Has two planets. The first is at least a 4.5 ME Super Earth (0.16 AU) and is the oldest Potentially Habitable Planet. The second is over 7 ME and beyond the HZ (0.3 AU).
- 14.8 ly - Gliese 674 System - CD-46°11540 is most commonly known as Gliese 674 and informally Proxima Arae. It is the nearest red dwarf known to have a planet and was the second nearest known exoplanet to the Sun when discovered. The star is type M3 V and is about 35% as massive and 42% as wide as the Sun and believed to be 550 million years old. It was once classed as an orange dwarf and a possible sub-dwarf. It was discovered by John Tome at Cordoba in Argentina. The planet is a Hot Neptunian in a tight orbit that has a similar eccentricity as Mercury. It's about 70% the mass of Neptune and 12 times that of Earth. It is unclear what its nature would be. It orbits at 0.04 AU, which is closer than the habitable zone, which is 0.13 to 0.15 AU.
- 15.4 ly - Gliese 876 System - 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.
- 16.1 ly - Gliese 832 System - CD-49°13515 is most commonly known as Gl 832, and also L 354-89, DM-49°13515, and HD 204961. It is the third nearest red dwarf with planets and in the constellation Indus. It can be considered a miniature version of the Solar System, with a large gaseous planet in a far orbit, and a smaller potentially rocky planet interior. Has a slightly eccentric Jovian planet with 64% Jupiter's mass at an asteroid-belt like distance. The planet has the second largest angular separation from it star of any known planets and is further from its star than any other red dwarf orbiting planet. A good astrometry detection candidate and a target for SIM. One of the larger red dwarf planets around one of the larger (M1.5) red dwarves (about half a Solar Mass). It also emits x-rays. Super Earth planet c is the most Earth-like known exoplanet, and one of the top three potentially habitable planets, but is more likely a super Venus. A third Earth-sized planet could exist between these planets.
- 19.8 ly (*) - 82 Eridani System - 82 G. Eridani is also known as 82 Eri, HR 1008, Gl 139, and HD 20794. One of the nearest star systems with planets. It is one of the dimmer yellow dwarf stars. Has three radial velocity detected super Earth planets orbiting closer than the habitable zone. The outermost one d is the largest (5 times Earth's mass, twice its radius, rocky-water composition) is about the same distance as Mercury is from the Sun. The middle one c is 0.1 au closer and is the smallest (2.5 Earth's mass, 1.5 its radius) and is likely a rocky-iron in composition. The innermost one is at 0.1 AU and just slightly larger than c, but more massive and of a more rocky-water composition. A dust disk was also found about 20AU from the star. The 2007 book "Habitable Planets for Man", released prior to the discovery of the planetary system, placed this as the most habitable star system within reach of mankind.
Systems Within 10 Parsecs (33 ly)Edit
20.4 ly - Gliese 581 System - 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.
23 ly - Gliese 667 System - MLO 4 is most commonly known as Gliese 667 and also known as HR 6426 and HD 156384. A triple star system 23 light years away that contains planets in Scorpius. It was first cataloged as a binary star by astronomers at the old Melbourne Observatory (MLO) in Australia in 1867, so it was cataloged as MLO 4. It consisting of binary of orange dwarf stars about 12 AU apart (ranging from 5 to 20 AU), around which a distant red Dwarf C orbits (ranging from 56 to 215 AU). Star C is a dynamically packed planetary system, with at up to 7 unconfirmed super-Earth planets. The system became the nearest multistar system with planets when planet b (innermost, largest), a temperate super Earth planet (5.7 ME, 0.05 AU) was discovered, and is at the very inner edge of the most generous habitable zone. It became the poster child for an announcement of 32 exoplanets discovered by European astronomers working on the HARPs project and brought the total number of exoplanets to near 400. Planet c was later discovered near the inner edge of least generous habitable zone and is about the same size, and receives the same amount of stellar energy as the Earth. It was calculated that it likely no longer has a magnetic field that could protect its oceans from stellar radiation. Planets f and e were confirmed and also orbit in the Hz further out. Planet d is just beyond he HZ. Outermost planet, g (2.4 ME) is likely a frozen planet and the only one beyond Mercury-like distances. The multi-planet solution is somewhat lax and complicated and may need further confirmation. An even more unconfirmed planet h may be between b and c. A fourth stellar companion D is not gravitationally bound to the system.
25.1 ly - 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.
28 ly - 61 Virginis System - A system containing a 5.1 ME Hot Super-Earth b (which is hot enough to have emissions on its night side) and one and possibly two other further out Neptunians (c and d [unconfirmed] and possibly a fourth), and a massive Kuiper Belt around a very Sun-like star only 28 light years away. All planets would fit inside Venus' orbit and have high eccentricities, especially the outermost one. This is the closest planetary system around a G-type star, which is one of the only very sun-like stars visible to the naked eye. It is the first non-borderline G-class main sequence star found to have a super-Earth. A lack of a Jovian planet and an unseen further out Neptunian may explain the large amount of cometary debris detected. Systems like this may avoid a heavy bombardment period, but instead undergo a steady rain of occasional cometary impacts for billions of year. Of the six sunlike stars within 10 parsecs, this star would be the one most likely to have an older version of Earth orbiting it. This postulated planet would have only microbes left as its star became hotter.
28.6 ly - Gliese 849 System - BD-05°5715 is best known as Gliese 849 and also known as LHS 517. Nearby red dwarf star system in Aquarius with a planet. Contains the first long period exoplanet found around a red dwarf star using dopplar spectrometry. Also only the second Jupiter mass planet around a star less massive than half the Sun. Also the first confirmed Jupiter-sized planet at Neptune-like temperatures. There is evidense for a second planet.
29 ly - Gliese 433 System - Contains one of four super-Earths announced by the HARPs team in October 2009.
29.9 ly - Gliese 317 System - The smallest red dwarf within 10 parsecs with planets and the third red dwarf with detected planets. Has one eccentric long period Jovian and possibly a second very eccentric longer period Jovian in a resonant orbit.
30.7 ly - Gliese 176 System - BD+18°683 is also known as Gl 176. It is a nearby red dwarf with a low period neptunian in Taurus. It was likely first catalogued in the Bonn Survey published in 1863 and its high proper motion discovered by Ross. Planet is the fourth discovered Neptunian around a Red Dwarf star. Categorized as a gaseous Hot Superterran with a metals-rich atmosphere. Mnemonic: BD Taurus.
33.5 ly - Gliese 436 System - 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.
Systems Within 50 Light YearsEdit
36.2 ly - 54 Piscium System - 54 Piscium is a nearby orange dwarf star also known as HR 166, Gl 27, Hip 3093, HD 3651. Has an eccentric planet about the mass of Saturn orbiting at Mercury-like distances. A recently discovered faint distant T type brown dwarf 476 AU away was found to be the cause of this eccentricity, which was directly imaged.
39.2 ly - Gliese 86 System - Contains the first exoplanet discovered by CORALIE of the Geneva southern extrasolar planet search programme. A cloudless blue heavy jupiter and a white dwarf around an orange star.
38.4 ly - Errai System - Also known as Gamma Cephei, an orange sub-giant (1.4 MS, 4.8 RS, 6.6 GY) with a 1.6 MJ "Sulfurous Cloud Giant", Tadmos, in an eccentric orbet centered at 2 AU (1.8 to 2.2 AU) and a red dwarf (0.5 MS) at 20 AU (11.9 to 28.3). Located 45 ly away at the northern tip of the constellation and one of the brightest stars near Polaris and will succeed Polaris as the North Star (closer to pole in 3000 AD, and at closest in 4000 AD). It is the first close in binary star found to have a planet. The planet was first detected in 1988, and could have been the first discovered, but wasn't confirmed until 2002. Could be called the first real exoplanet detected. One of the first 20 exoplanet systems allowed to be given common names by the IAU. Named after an ancient Syrian city.
41.0 ly - HD 69830 System - First planetary system found that does not have a Jupiter-sized planet around a normal star (K0 spectrum). Contains 3 Neptunians and the first discovered asteroid belt that is like the size and age as the Sun's. The debris from this belt that was detected was from the breakup of an asteroid, is 20 times as massive as our own, and would cause zodiacal lights 1000 times brighter than we see from Earth. The smallest and outermost planet may be a 10 ME super Earth, is within the habitable zone, and is an inner shepherd for the asteroid belt. Halo 3 features a fictitious moon around this planet.
42.0 ly - 51 Pegasi System - 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.
42.1 ly - HD 147513 System - A jovian and white dwarf around a yellow dwarf.
43.7 ly - 55 Cancri System - Copernicus is also known as Rho Cancri, 55 Cancri, Rho1 Cancri, HR 3522, Gl 324, and HD 75732. Wide binary star consisting of a sun-like primary (A, though super metal rich) and a red-dwarf secondary (B) separated by 1,100 AU, 41 light years away. Star A contains five exoplanets, the first system found with four or five planets. It has three tightly packed eccentric planets close in to the star, including planet Jannsen (e, hot Super Earth/Neptunian), Galileo (b, warm Jupiter), and Brahe (c, hot Saturn), followed by an eccentric Saturn in the habitable zone (Harriot, f) and a Jupiter analog, Lippershey (d). Planet e was heralded as the first Neptunian discovered. It was later found to be the shortest-period planet discovered (18 hours) and to transit. Its density was measured and determined to be rocky, and thus re-dubbed the first Super-Earth discovered. It was then the first super-Earth to have its light detected (by Spitzer in the infrared). The planet has about half of Neptune's mass, but is Earth-like in size and density (2.17 Earth Radius). Studies taking into account the composition of the star suggested that it was largely made of diamond, with graphite at the surface (the first diamond planet around a Sunlike star), and the first terrestrial found with fundamentally different surface composition and processes than Earth. This was later refuted when it turned out there wasn't as much carbon in the parent star as believed. Earlier studies that assumed an Earth-like composition suggested that it would be covered with an ocean of super-critical water. The brightness of the planet was found to have raised dramatically, possibly the aftermath of cloud cover due to a volcanic eruption. The brightness of the star (also closest known to transit and only known naked eye star to do so) makes it more easily studied than other hot super Earths. It was found to be dark and its sun-facing side hot enough to melt metal. It became the first super Earth to have its atmospheric composition measured (mostly hydrogen and helium with hints of hydrogen cyanide which would only dominate in a carbon-rich environment and no traces of water vapor) and temperature mapped, and the large hemispherical temperature differences suggest little atmosphere to transport heat. Planet b (one of the original 4 Hot Jupiters discovered) is the first "warm Jupiter" found to have a puffed up atmosphere and it probably at the outer limit from the star at which a planet can lose its atmosphere in this way. Its outer atmosphere skims the surface of the star, which was detected when attempting to detect an atmosphere around transiting Janssen. The strong interaction between planets Galileo and Brahe can be detected in measurements, and it took a while to find a fit that would allow them to survive over long periods of time. Harriot is a very eccentric Saturnian in the habitable zone. Planet d is a super jovian at Jupiter-like distances, which was the first found at true Jupiter distances and still the exoplanet discovered with dopplar spectrometry with the largest known semi-major axis. It was first thought to be circular, then eccentric, and then circular again. The distant outer star causes Lippershey's axis to flip on its axis every million years. Lippershey in turn causes the other planets to flip, including its star. The axis tilt of transiting planet e should be determined at some point. "Bode's law" predicts four undiscovered planets. One of the first 20 exoplanet systems allowed to be given common names by the IAU.
44.0 ly - 47 Ursa Majoris System - (aka Ursae Majoris) Chalawan (aka 47 Ursae Majoris) is solar analog (G1 V, about the same age as the Sun) with 3 planets 46 ly away. One of earliest systems discovered. Taphao Thong (b, 2.5 MJ, 2.1 AU) and Taphao Kaew (c, 0.5 MJ, 3.6 AU) are in circular orbits at asteroid-belt like distances, while planet d (1.6 MJ, 11.6 AU) is in a distant more eccentric orbit (0.16, 9.6-13 AU). Planet b was the first found to have a circular orbit beyond the habitable zone. The discovery of planet c made the system the first multiplanet system whose planets have circular orbits, and b and c are rough Jupiter-Saturn analogs in relative size and positions. Their existence was in doubt until planet d was discovered. Planet d has not yet completed a full year (38.4 years) yet since its discovery (it cannot be named yet), but is the furthest out planet discovered with the dopplar spectrometry method. Studies have shown a terrestrial planet could only form in the innermost part of the habitable zone. Several transmissions have been sent to the star system. One of the first 20 exoplanet systems allowed to be given common names by the IAU. Star named after a Thai crocodile asterism and its planets are associated with two sisters associated with this legend. Taphao Thong was captured by the crocodile, while her sister Taphao Kaew married the one who rescued her.
52.0 ly - Upsilon Andromedae System - Titawin (Upsilon Andromeadae) is a nearby (44 ly) multi-star system which is the first multiplanet system found around a main sequence star or a multi-star system. The main star around which the planets orbit is a yellow-white star somewhat younger than the sun and its companion is a red dwarf in a wide orbit. It is one of the most well studied non-transiting star systems. Roaster Saffar (b, 0.05 au, 0.62 MJ, e=0.013, and the nearest true Hot Jupiter to Earth) is nicknamed the Fire and Ice Planet because it is hot on one side and cold on the other. The hottest parts of the planet are near the trailing side terminator at the equator, due to high velocity winds transporting heat to the night side. This is 80deg offset from the starward pole and a much greater offset than other observed hot Jupiters. This threw astronomers off and caused them to doubt the wind-theory, though later observations of other planets have shown that winds indeed can travel fast enough to cause this. Stability studies and observations suggest its diameter is 1.8 DJ, rather large for a planet its age. The middle planets Samh (c, 0.83 au, 1.8 MJ, initially thought to possibly be a brown dwarf star, e=0.224) and Majriti (d, 2.5 au, 10.2 MJ, e=0.26) have had their inclinations and masses determined with astrometry, the first determination of relative inclinations of exoplanets. They are very eccentric and highly inclined to each other (30 deg). Planet scattering was thought to be a source until the outermost planet was discovered. This is planet e (5.2 au, 1.05 MJ, e = 0.005), which is the most Jupiter-like exoplanet known, and is in 3:1 resonance with planet d. Planet c is in the habitable zone, though any habitable moons would see drastic temperature swings. The star appears to have no Kuiper-belt like disc, perhaps due to its companion star sweeping away this material. One of the first 20 exoplanet systems allowed to be given common names by the IAU. The star is named after an important city in Morocco that bridged the Spanish and Arab worlds. The planets are named after famous Andalusian astronomers.
Systems Within 100 Light YearsEdit
63.4 ly - 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.
Systems Within 100 ParsecsEdit
Systems Within 1000 Light YearsEdit
Systems Within 1000 ParsecsEdit
Systems Within 10000 Light YearsEdit
Systems Within 10000 ParsecsEdit
Systems Beyond 10000 ParsecsEdit
Other Important Systems within 10 parsecEdit
11.8 ly - Epsilon Indi System - Epsilon Indi is the also known as HR 8387, Gl 845, and HD 209100. Second nearest single sunlike star to the Sun. Orange dwarf with a binary brown dwarf orbiting it. The smaller of the two is the closest thing to an "extrasolar moon" found so far. The constellation "Indus" first appeared in 1603 in the Uranometria. Epsilon Indi appeared as one of the Indian's arrows in Bode's 1801 atlas, the Uranographia. The star's high proper motion was first discovered by Gill in 1882, which was improved upon by Shapley in 1923. During 1960, the star was observed for radio signals, but none was found. In 1972, it was searched for ultraviolet laser signals. It leads a Carnegie list of stars most likely to have an earth-like planet. The star's age has been controversial, at first thought to be older than the sun, then younger, then even older than originally thought, all based on studies regarding the brown dwarf's nature and the rotation rate of the star.
11.9 ly - Tau Ceti System - Tau Ceti is also known as HD 10700, HR 509, and Gl 71. The nearest single G-class yellow dwarf to the sun, somewhat smaller than the Sun. A popular science fiction subject and one of two targets of SETI-forerunner Project Ozma in the 1960s. Despite being somewhat older than the sun, it has an extensive asteroid and/or comet field 10-50 AU, with the bulk between 35 and 50 AU. It has about ten times as much material as the Sun. This would make life difficult. It is a metal deficient star, so it is thought less likely to host rocky planets. Traditional dopplar spectrometry has ruled out any large Jupiter sized planets at Jupiter like distances or closer in, which was thought to be good for any potentially habitable planets. Five candidate rocky super Earth planets were detected though using a new method of planetary detection. This method made predictions of the stellar "noise" activity that might obscure detection of a planet based on the long history of dopplar measurements done on this system. Deviations from this prediction pointed towards the existence of planets. Confirmation using more established methods is needed. These planets are labeled b through f as you go outward, span 0.1 AU to 1.35 AU, and get larger the further you go out (at least 2 ME to 6.6 ME). The outermost two are near the habitable zone and were originally hailed as possibly being the nearest and smallest known habitable planets. More recent modeling indicates they are not actually habitable though. Planet e is probably too close to the star and only in the HZ if generous assumptions are made. Planet f has probably only been in the habitable zone for about a billion years as a result of its star becoming hotter, which might make biosigns difficult to detect from Earth, considering it took 2 BY for biosigns to become detectable around the Earth. Since the star has a higher magnesium to silicon ratio than the Sun, these planets compositions could be quite different that the Solar System's. The lower mantles could be dominated with ferropericlase, which is not very viscious, which may make the rocks of the mantle flow easier than on Earth, affecting volcanism and tectonics. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation.
13.2 ly - DENIS 1048-39 System - A free floating brown dwarf or red dwarf.
16.3 ly - LP 944-20 System - A free floating brown dwarf.
18.7 ly - 2MASS 0415-0935 System - 2MASS J04151954-0935066 is abbreviated as 2MASS 0415-0935. It is a nearby T-Class brown dwarf in Eridani. It was the coolest brown dwarf known when discovered in 2002.
18.8 ly - Gliese 229 System - A brown dwarf around a red dwarf.
19.3 ly - Gliese 570 System - A triple star system with a brown dwarf.
26.0 ly - Vega System - Vega is also known as Alpha Lyrae, HR 7001, HD 172167, and Gl 721. It is the fifth brightest star in the night sky the second brightest star visible from the Northern hemisphere, and brightest star in the Northern Summer. It is part of the Summer Triangle. It was the first star to be photographed in 1850. It is a slightly bluish star (A0) with about 2.15 times the sun's mass and 2.7 its diameter. It was at first estimated to be about 200 Million Years old, but now thought to be closer to 700. It was found to be rotating so fast that the equator bulges significantly (23%) and is cooler at its poles. Nearby star with one of the first detected circumstellar disks. The star is pointed nearly pole-on from the Earth, so it is ideal for the observation of dust disks. There have been many studies suggesting planets are responsible for features found in the disk. Two bright "clumps" of dust were identified and thought to be due to the gravitational effects of an eccentric planet's orbit. It was surmised that this disk was caused by a collision between Pluto sized objects. A distinct asteroid belt and kuiper belt at distance scales that dwarf our Solar Systems was found to exist, which suggest outer planets clearing out the space in between. These planets cannot be detected at the present, but could be detected by the James Webb Space Telescope. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation.
32.4 ly - AU Microscopii System - AU Microscopii is also known as Gl 803, HD 197481, and CD-31°17815. It forms a triple star system with the double red dwarf star AT MiC, located 1.2 ly away, which are also known as Gl 799, HD 196982, and CD-31°16135. An active flare star and about 12 Million Years old. First red dwarf found with a circumstellar disk and the nearest planetforming disk. Also the first system where particle size in disk determined. Constraints on where planets could exist was recently published. Patterns in the dust disks suggest planets. It is thought that Pluto-sized planetoids may have formed in the outer system. AT MiC A and B are separated by 24.2 to 40.8 AU, and are somewhat smaller than AU MiC. All components are part of the Beta Pictoris Moving Group.