| Exoplanetary Scratchpad|
Systems Within 10 Light YearsEdit
- 0 ly - Solar System - Our home star system. Contains 4 terrestrial planets, 4 gas giant planets, several dwarf planets, an asteroid belt, and a kuiper belt, around a G-Class yellow dwarf star. Contains the only known habitable planet, Earth.
- 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.
- 5.9 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 once thought to have a planet around it found due to radial velocity method. Since disproven. A potential target for the 1970's Project Daedelus. It has been determined definitively that no Earth-sized planets orbit in its habitable zone. The nearest system without known planets. 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.
- 7.8 - Wolf 359 System - Wolf 359 is also called Gl 406, and CN Leonis and informally called Proxima Leonis. Third nearest star system to the Sun. It is one of the smallest Red Dwarf stars known and is a flare star and the M6 V spectral standard star. Its proper motion was first measured by German astronomer Max Wolf in 1917. It was the lowest mass and faintest star known until the discovery of VB 10 in 1944. Its temperature is so low that chemical compounds can exist in it, which is rare for a star. It is a relatively young star, less than a billion years old.
- 8.25 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. 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.
- 8.6 ly (*) - Sirius System - Sirius is also known as Alpha Canis Majoris and Gliese 244. The brightest star in the sky. A hot blue-white main sequence star with a white dwarf (the "pup") orbiting it. Orbit distance varies between 8.1 and 31.5 ly and takes 50 years to navigate. The habitable zone of Star A is centered 4.25 AU from the star and may be disrupted due to the presence of Star B. Long thought to be a part of the Ursa Major Moving Group (also called the "Sirius Group"), it was found to be too young to be a member and not heading in the right direction. The brightest star within a large distance from the Sun. Star B is about the same mass as the Sun, but is almost the same size as the Earth. It may have evolved from a 5 solar massed B-type main sequence star. It is the nearest and first discovered white dwarf star. Dust has been detected from the system, probably from material sluffed off from Star B. A search in 2008 using high contrast imaging for planets within 10 Jupiter masses within 25 AU of the binary star turned up negative.
- 8.7 ly - UV Ceti System - Luyten 726-8 is also known as Gliese 65 and Luyten 726-8 and informally Proxima Ceti. It is the 6th nearest star system to the Sun. Nearby binary star system of red dwarves a distance of 2 to 9 AU from each other. Star A is also called BL Ceti, while Star B is the most famous flare star, called UV Ceti (arch-type for UV Cetic class flare stars). In 31,500 years, it will pass within only 0.93 ly of Epsilon Eridani, which may stir up comets in any Oort Clouds in these systems. It is possibly a member of the Haydes Stream.
- 9.7 ly - Ross 154 System - Ross 154 is also called Gliese 729 and informally Proxima Sagittarii. Nearby flare star that experiences major flares about once every 2 days. An exceptionally large red dwarf and probably young, which explains the flares. First cataloged by Frank Ross in 1925.
Systems Within 20 Light YearsEdit
(includes all stars brighter than Red Dwarves and all Red Dwarves closer than the closest know Red Dwarf with planets)
- 10.3 ly - Ross 248 System - Ross 248 is also called Gl 905 and informally Proxima Andromedae. Nearby Red Dwarf flare star system dubbed HH Andromedae. There are indications of perterbations caused by an unseen companion, but searches for a brown dwarf star failed to find anything. It will become the nearest star to the sun in 33,000 years. Voyager 1 is heading in the direction of Ross 248 and is expected to be 1.76 light years from it in 40,176 years. It is currently very close to Groombridge 34, which is only 1.8 light years away, and could be visible from that star.
- 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.
- 10.7 ly - Lacaille 9352 System - Lacaille 9352 is also called Gl 887 and HD 217987 and informally Proxima Piscis Austrini. Nearby red dwarf star with about half the sun's mass and radius. It is the second bright red dwarf in the sky, but is too dim to see unaided. Its high proper motion was discovered by Gould.
- 10.9 ly - Ross 128 System - Ross 128 is also called Gliese 447 and informally Proxima Virginis. Nearby Red Dwarf star system. Planet b is the second closest known exo-Earth and the closest temperate planet known around a quiet star. Thought to be the best candidate for a potentially habitable exoplanet.
- 11.1 ly - EZ Aquarii System - EZ Aquarii is also called Gl 866, L 789-6, and informally Proxima Aquarii. Nearby triple red dwarf star system, all near the lower limit of hydrogen burning of 75 Jupiters. All three put together is about a third of the Sun's mass. A (M5Ve) is only 11% as massive as the sun and 15% its diameter. Its high proper motion was first discovered by Luyten. A and B are in an eccentric orbit separated by 1.2 AU on average. A also has a spectroscopic binary companion C which has a period of only 3.8 days. C is so small that it's possible that it's a brown dwarf, though probably not. The stars are close enough to interfere with each other's habitable zones. It's possible a habitable planet exists around B, but flares would make this difficult.
- 11.4 ly (*) - Procyon System - Procyon is also known as Alpha Canis Minoris, HD 61421, and HR 2943. Nearby Bright star system. Nearest yellow white star (F5 IV–V) to the Sun and the closest star to Sirius. It is the 7th brightest star in the sky. Has a white dwarf companion B. Has about 50% more mass than the Sun and about twice its radius. It is a BY-Draconis type of variable (unusual for a bright star) and entering the last stage of its life on the main sequence, heading towards a sub-giant, as its core seems to have exhausted its supply of Hydrogen and is starting to fuse Helium. Its habitable zone, which is 2 to 4 AU, may be disrupted by B, which is only 9 to 21 AU away. Star B was first predicted due to its effect on A's proper motion in 1844 and later spotted in 1896. It was probably about the same mass as Star A, and sterilized the system when it went into a giant phase. Luyten's Star is only 1.2 light years away, near enough to stir up any Oort clouds in either system and would be dimly visible.
- 11.4 ly - Struve 2398 System - Struve 2398 is also called Sigma 2398, BD+59°1915, DM+59°1915, and Gl 725, and informally Proxima Draconis. It is a nearby binary red dwarf system. The distance of the two component stars was first measured by Friedrich von Struve in 1832. Star A is also known as HD 173739. It is inaccurarely referred to as a K type star in some catalogs. Star B is also known as HD 173740. Their distance ranges from 19 to 65 AU. An observer from Star A would see Star B as a point about as bright as the full moon.
- 11.4 ly (*) - 61 Cygni System - 61 Cygni is also called Gl 820, very rarely called Bessel's Star, and informally Proxima Cygni. Nearby star system containing two orange dwarves. This was the star with the highest proper motion known in the 1830s and dubbed as "The Flying Star" by Giuseppe Piazzi in 1792. It is the star with the highest proper motion of any stars visible with the naked eye. In 1911, it was found by Boss to be a part of a moving group, dubbed the 61 Cygni Moving Group. Friedrich Struve first made measurements of it as a binary system in 1830. It was also the first system to have its distance measured by parallax, which was done by Bessel in 1838. The stars are barely visible with the naked eye. The stars are separated on average by 86 AU. The stars atmospheres likely do not touch. The stars are old, 6 to 10 Billion Years old. There were several claims of a planetary system in the 20th Century, but none have panned out. This includes Strand's claim in 1942 (under the direction of Van de Kamp), and Soviet claims in 1977. Heintz proved in 1978 that these claims were false. Due to its proximity to Earth, the star was a tier 1 priority for the Space Interferometry Mission, which hoped to discover planets.
- 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.
- 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.
- 11.8 ly - DX Cancri System - DX Cancri is also known as G 051-015, GJ 1111 and informally Proxima Cancri. It is a nearby red dwarf flare star designated. A "spectacular" flare was detected in 2006. A search for a dust disk was undertaken, but none was found. This is thought to be a member of the Castor Moving Group. Its proper motion may first have been noticed by William Luyten.
- 11.9 ly - LHS 1565 System - LHS 1565 is also known as L 372-58m, LTT 1702, GJ 1061 and informally called Proxima Horologii. Nearby Red Dwarf star system. Measurements in 1997 found it was a lot closer than it was once thought to be at 11.9 ly.
- 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.
- 12.1 ly - YZ Ceti System - YZ Ceti is also called L 275-22 and Gl 54.1. It is a nearby Red Dwarf flare star that's only 1.6 ly from Tau Ceti.
- 12.4 ly - Luyten's Star System - Nearby Red Dwarf star system also known as BD +05°1668 (sometimes called Luyten 5-1668) and Gl 273. It is in Canis Minor. Named after William Luyten, who with Edwin G. Ebbighausen, first determined its high proper motion in 1935. It is at the maximum mass that a star can be fully convective (ie, the entire star has a single convection zone). It is the closest star to Procyon (1.2 ly), which would appear as -4.5 magnitude star in any of its planets skies.
- 12.6 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).
- 12.6 ly - Teegarden's Star System - Teegarden's Star is also called SO 025300.5+165258 or SO 0253+1652 and informally Proxima Arietis. Nearby Red Dwarf star system with flares. It was found in 2003 by inspecting photographs used to discover near earth asteroids, whose motion can spot nearby stars with high proper motion. Only six other stars have a proper motion of more than 5 arcseconds per year.
- 12.6 ly - SCR 1845-6357 System - A Red Dwarf star only 11 ly away with a T-Type Brown Dwarf.
- 12.9 ly - Lacaille 8760 System - Lacaille 8760 is also known as Gl 825 and informally Proxima Microscopii. Considered the brightest red dwarf in the sky, though it is sometimes listed with a K spectral type. It is just barely possible for someone with exceptionally good eyesight to see under the ideal conditions. Its orbit is rather tilted and eccentric. Its high proper motion was first noticed by Carl Moestra in 1875. It is a variable star known as AX Microscopii, but does not have devastating flares which would disrupt life. The habitable zone would be from 0.27 to 0.53 AU.
- 13.1 ly - Kruger 60 System - Kruger 60 is also known as BD +56°2783 and Gl 860. It is a nearby pair of Red Dwarfs. B is a flare star known as DO Cephei, which would probably prevent life from developing on any planets. Their distances vary from 5.5 to 13.5 AU. B would appear as a point as bright as the full moon from A. In 88,600 years, it will come closest to the Sun at 6.4 light years, compared to its present distance of 13.1 ly.
- 13.2 ly - DENIS 1048-39 System - Nearby brown dwarf.
- 13.4 ly - Ross 614 System - Ross 614 is also called Gl 234. A nearby binary Red Dwarf. Star A is the flare star known as Nearby V577 Monocerotis. First discovered by Ross in 1927 and then Star B was discovered in 1936. Star B has long been considered the quintisential low mass star. Unfortunately its long period of 16.6 years makes it difficult for most studies to observe. They're separated by 2.4 to 5.3 AU.
- 13.8 ly - Wolf 1061 System - BD-12°4523 is also known as Wolf 1061 and Gl 628. Nearby red dwarf flare star also called V2306 Ophiuchi. It is possibly a binary star. Has three super Earths, at 0.03 (1.4ME+), 0.08(4.3ME+), and 0.2 AU (5.2 ME+). Had the nearest potentially habitable planet, about 4 Earth masses.
- 14.2 ly - Wolf 424 System - Wolf 424 is also known as Gliese 473. Nearby binary Red Dwarf separated by about 2.36 to 4.19 AU with a period of 16.2 years. The secondary star is a flare star known as FL Virginis. At one point, it was thought that these could be high massed Brown Dwarves, but this has been disproven.
- 14.2 ly - Cincinatti System - Nearby Red Dwarf.
- 14.6 ly - TZ Arietis System - TZ Arietis is also known as L 1159-16 and Gliese 83.1. Nearby Red Dwarf flare star.
- 14.8 ly - BD+68 946 System - Gliese 687 is also known as BD+68 946. It is a nearby binary Red Dwarf.
- 14.8 ly - LP 731-58 System - LP 731-58 is also known as LHS 292 and NN 3622 and informally as Proxima Sextantis. Nearby red dwarf star with frequent flares.
- 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.
- 14.8 ly - V1581 Cygni System - V1581 Cygni is also known as GJ 1245. Nearby triple Red Dwarf star system. Star A is only 11% the Sun's mass and is also known as G 208-44 A and LHS 3494. C is 8 AU (7% Sun's Mass) from A and is also known as G 208-44 B. It is one of the more well known tenuous red dwarfs and is only an M8 in spectral type. B is 33 AU away (10% Sun's Mass) and is also known as G 208-45 and LHS 3495. B would appear as bright as Venus does from A.
- 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.
- 15.9 ly (*) - Groombridge 1618 System - Groombridge 1618 is also known as Gl 380 and HD 88230. Nearby orange dwarf system in Ursa Major. It is an unusually bright flare star, but flares less frequently than other such stars. Its level of activity suggests it is relatively young, perhaps a little older than a Billion years. First identified in A Catalog of Circumpolar Stars by Stephen Groombridge, published posthumously in 1838. An unconfirmed planet was published in 1989 with 4 Jupiter masses at about half Earth's distance, in the inner part of the star's habitability zone. It's signal could be due to stellar activity. Its closest neighbor is a red dwarf UX UMa, which would flicker in and out of visibility due to the effects of its flares.
- 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.
- 16.2 ly - DENIS 0255-4700 System - DENIS 0255-4700, first identified as an object of interest in 1999, was found to be the nearest class L Brown Dwarf, the faintest type of brown dwarf, to the Solar System in 2006. It was the faintest object beyond the solar system to have its intrinsic brightness measured. In Eridanus.
- 16.5 ly (*) - 40 Eridani System - Kied is also known as 40 Eridani, Omicron 2 Eri, and Gl 166. Triple star which is Gene Roddenberry's favored location for Spock's home planet of Vulcan. Consists of an Orange Dwarf primary A (also called HD 26965 and HR 1325) with a flare star Red Dwarf C (also called DY Eridani) orbiting 50 AU away, and a much further White Dwarf B at 600 AU. The white star would appear two orders of magnitude brighter than Venus does from any planets in AC, so it would be visible in the daylight. While no planet has been discovered in this system yet, it has been selected as a target for the SIM Planet quest when launched in 2015 for signs of a habitable planet. The White Dwarf is by far the easiest White Dwarf to observe, as it is brighter than the closer Van Manaan's Star and is not swamped by the light of a bright primary like those found in the Sirius or Procyon systems.
- 16.6 ly (*) - 70 Ophiuchi System - 70 Ophiuchi is also known as GJ 702 and HD 165341. It is a nearby pair of orange dwarves, easily visible with the naked eye when away from city lights. Star A is a DY Draconis variable star and is also known as HR 6752. It was first cataloged by William Herschel in the late 18th century during his study of binary stars, who claimed Father Meyor noticed its duplicity earlier (whose other claims could not be verified by contemporaries). He proved the two stars went around each other, an important verification of Newton's laws. He suspected another object was affecting the orbits of the two stars. Other astronomers claimed this could be a planet, such as Captain Jacob in 1855, which is one of the first claims for a planet using astrometric data. See also made a claim in 1899, but Moulton soon published a paper showing that this system would be unstable. In 1943, Reuyl again caused a sensation by claiming planets, only to be refuted again. The two stars follow an eccentric orbit ranging from 11.7 to 34.8 AU away. Star A has about 92% of the Sun's mass. The stars are thought to be 1.5 Billion Years old.
- 16.7 ly (*) - Altair System - Altair is also called Alpha Aquilae, GJ 768, HD 187642, and HR 7557. Second nearest A main sequence class star, on the verge of becoming a sub-giant, and about 1 Billion years old. One of the stars of the Summer Triangle and 12 brightest star in the sky. It is a particularly rapidly spinning (9 hours) and flattened (20%) star. It has 1.7 the Sun's mass and 1.8 its diameter. Its brightness fluxuates slightly, classifying it as a Delta Scuti variable star and given a New Suspected Variable star designation of NSV 24910. In 2006, it became the first star to be directly imaged (in the infrared) other than the Sun. Its equator is darker than its pole due to its rapid rotation, which was visible as a white spot in images. No planets have been detected and there are some theoretical reasons for why a star rotating so quickly might not have planets. It has two visual companions that are not bound to it, but merely close to it in the sky. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation.
- 18.8 ly (*) - Sigma Draconis System - Alsafi is also known as Sigma Draconis, HR 7462, Gl 764, and HD 185144. It's name is from derived from Arabic for a "cooking tripod" that nomads used. It has been reclassified in 2003 as a G9 Yellow Dwarf star (it was thought to be an orange dwarf). It has about 90% of the Sun's mass and 80% of its diameter. There appears to be a sunspot cycle, though its length is undetermined, and it was found to be the least variable of any of the stars observed by Hipparcos. It is thought to be 7 to 8 Billion Years old. It was a tier 1 target for Nasa's Terrestrial Planet Finder and a top target for ESA's Darwin project before both projects were put on indefinite hold. It was described as being the fourth easiest star to find terrestrial planets. No indication of any planets or dust disks have so far been detected. One of 5 PICTURE-C targets selected for sub-orbital coronograph observation.
- 19.3 ly (*) - Gliese 570 System - Nearby star system.
- 19.4 ly (*) - Eta Cassiopeiae System - Archird is also known as Eta Cassiopeiae and Gliese 34. Nearby yellow dwarf star (A) orbited by an orange dwarf star (B). It is the brightest star near the lines formed by the "W" of the constellation. Star A is also known as HR 219, LHS 123, and HD 4614, while Star B is also known as LHS 122. Star A is about the same size, mass, and age as the Sun, but only about 65% as metal rich. It represents what the Sun might look like from Archird. Its habitable zone is centered on 1.35 AU. At one time, Star A was thought to have a spectroscopic binary companion with a nine day orbit period. Star B may have first been discovered by William Hershel in 1779 two years prior to discovering Uranus, while he was seeking nearby double stars for parallax studies. Star B ranges from 36 to 107 AU. It has 56% of the Sun's mass and 66% it diameter, but only 3% its luminosity. Radial velocity variations have been detected, though no planet has been announced at this time. The system is a top tier target for TPF. In Star Trek, this is home to Terra Nova.
- 19.5 ly (*) - 36 Ophiuchi System - 36 Ophiuchi is also known as Gl 663. A nearby triple orange dwarf star system. Stars A and B have extremely eccentric orbits and their distance varies from 7 to 169 AU and are bright K0/K1 stars. Star A is also called HR 6402 and 155886, while Star B is also called HR 6401 and HD 155885. Limits have been placed on planets in this system and orbits beyond 1.5 AU may not be possible. Gliese Star C lies 5,000 AU away and is a dimmer star. It is also known as Gl 663C and Gl 664 and HD 156026. It is a RS CVn type variable star designated V2215 Oph. The system is relatively young at 1 to 1.8 Billion Years old and A is sometimes listed as a pre-main sequence star.
- 19.7 ly (*) - HJ 5173 System - HJ 5173 System
- 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.
- 19.9 ly (*) - Delta Pavonis System - Delta Pavonis is also known as Gl 780, HD 190248, and HR 7665. One of the nearest bright stars to the sun. Although somewhat smaller than the Sun, it is easily visible with the naked eye. It is about 6.8 Billion Years old. It has a New Suspected Variable designation NSV 12790 and appears unusually bright for a main sequence star, so may be starting to become a sub-giant. It was identified as the best SETI target of the nearest 100 G-type stars. It is the nearest solar-analog in a single system and is type G5-8 V-IV.