Thursday, July 19, 2007

Tau Ceti

Star type
g G8 Vp

Distance from Earth
g 11.9 ly
g To reach from Earth in 20 years, ship must average 0.61c

Star Service No.
g NA

Age
g Possibly up to 10 Gy

Diameter/Mass/Temp (xSol)
g 77%; 81%-82%; 5,500 K

Brightness (xSol)
g 59%

Metallicity
g 22%-74% percent of Sol's abundance of iron; considered metal poor

Comparison to Sol
g NA

Picture of star
g See picture

Star system features
g Relatively large and dense disk of cold dust around star; extending to around 55 AUs from the star, this dust is believed to be produced by collisions between larger comets and asteroids that break them down into smaller and smaller pieces, and Tau Ceti's disk is similar in size and shape to the disk of comets and asteroids that orbits the Sun
g Modeling of Tau Ceti's dust disk observations by the astronomers indicate, however, that the mass of the colliding bodies up to 10 kilometers (6.2 miles) in size may total around 1.2 Earth-masses, compared with 0.1 Earth-masses estimated to be in the Solar System's Edgeworth-Kuiper Belt (Greaves et al, 2004). Thus, Tau Ceti's dust disk may have around 10 times more cometary and asteroidal material than is currently found in the Solar System. Why the Tau Ceti System would have a more massive cometary disk than the Solar System is not fully understood. One theory is that Sol may have passed relatively close to another star at some point in its history and that the close encounter stripped off most of its comets and asteroids (Maggie McKee, New Scientist, July 7, 2004).

Known planets
g See paper "Signals embedded in the radial velocity noise"
g a - orbits star every 13.9 days; mass is 2 x Earth
g b - orbits star every 35.4 days; mass is 3.1 x Earth
g c - orbits star every 94 days; mass is 3.6 x Earth
g d - orbits star every 168 days; mass is 4.3 x Earth; in habitable zone
g e - orbits star every 640 days; mass is 6.6 x Earth
g Astronomers using the Hubble Space Telescope have failed to find a large substellar companion (large Jupiter or brown dwarf)

Habitable zone
g Distance from Tau Ceti where an Earth-type planet would be "comfortable" with liquid water is centered around only 0.68 AU - at about the orbital distance of Venus in the Solar System; such a planet would have an orbital period of about 228 days - less than two-thirds of an Earth year. Probability of a habitable planet is 3.6%.
g It is likely that any planet found to orbit within the star's dust disk would experience relatively frequent bombardment from asteroids and comets of the size that is believed to have wiped out the dinosaurs and other types of multi-cellular life on Earth. As a result, some astronomers have speculated that it is likely that with so many large impacts, large and complex forms of Earth-type multi-cellular life may not have had the opportunity to evolve and persist on inner terrestrial planets orbiting this star. Others (such as Glenn Schneider of the University of Arizona and Scott Kenyon of the Smithsonian Astrophysical Observatory), however, argue that a giant planet in the system could gravitationally deflect comets and asteroids away from inner planets that may support life in the liquid water zone, in the same way that Jupiter protects Earth in the Solar System. and her colleagues speculated that Tau Ceti is uninhabitable due to the large number of comets that appear to be buzzing around it (although this assessment may have been overly pessimistic, she now says).

Orbital map
g See animation

View from star
g See sky map

Nearby stars
(Star systems with 10 light years)
g YZ Ceti, 1.6 ly
g Luyten 726-8, 3.2 ly
g Epsilon Eridani, 5.5 ly
g Hip 15689, 5.9 ly
g Van Maanen's Star, 6.2 ly
g G 158-27, 7 ly
g L 1159-16, 7.1 ly
g Cincinnati, 7.5 ly
g LHS 1565, 7.6 ly
g Teegarden's Star, ~7.7
g Lacaille 9352, 7.9 ly
g L 722-22 AB, 8.1 ly
g EZ Aquarii 3, 8.8 ly
g LP 944-20 (brown dwarf), 8.9 ly

Map locating star system
g See stellar map
g See stellar map

Location in Earth sky
g Lies in the south central part of Constellation Cetus, the Whale - southwest of Baten Kaitos (Zeta Ceti) and northeast of Deneb Kaitos or Diphida (Beta Ceti)

Other names
g Tau Cet
g 52 Cet
g HR 509
g Gl 71
g Hip 8102
g HD 10700
g BD-16 295
g SAO 147986
g FK5 59
g LHS 146
g LTT 935
g LPM 84
g LFT 159

Sci-fi mentions
g In Isaac Asimov's Robot and Foundation novels, the planet Aurora and its two asteroidal satellites orbit Tau Ceti.
g In Robert A. Heinlein's novel Time for the Stars, the flagship Elsie encounters a few planets, and an Earth type planet, that they name "Constance". It is later colonized.
g In the Viagens Interplanetarias (Interplanetary Voyages) stories of L. Sprague de Camp its system contains the inhabited planets of Vishnu, Krishna and Ganesha, the second of these being the setting of his novels The Queen of Zamba, The Hand of Zei, The Hostage of Zir, The Virgin of Zesh, The Tower of Zanid, The Prisoner of Zhamanak, The Bones of Zora, and The Swords of Zinjaban.
g In Harry Turtledove's Worldwar series this is the home star of the invading aliens known as the Race.
g In Lois McMaster Bujold's Vorkosigan Saga series, Tau Ceti is occupied by a race of humanoids known as Tau Cetans
g In Larry Niven's Known Space series, the human colony of Plateau orbited Tau Ceti.
g The Legacy of Heorot (1987) by Larry Niven, Jerry Pournelle, and Steven Barnes takes place on the fourth planet of Tau Ceti.
g In Dan Simmons's Hyperion Cantos, Tau Ceti is orbited by Tau Ceti Center, capital of the Hegemony of Man.
g In Brian Antoine's online serial novella Tales of the Family nas Kan, a sci-fi/magic-based society of anthropomorphic animals inhabits a planet in the Tau Ceti system. See also furry fandom.
g In Ursula K. Le Guin's The Dispossessed, the action takes place in a fictional double planet system orbiting Tau Ceti. The two planets are called Anarres and Urras.
g In C. J. Cherryh's Hugo Award-Winning novel Downbelow Station, the space station referenced in the book's title (Pell Station) orbits a planet, Downbelow in the Tau Ceti system inhabited by the alien Hisa race.
g In Julian May's Galactic Milieu trilogy, Tau Ceti is orbited by the planet Molakar, inhabited by the alien race Krondaku, and destroyed in the Metapsychic Rebellion.
g Samuel R. Delany's Empire Star starts on a habitable moon circling a planet of Tau Ceti.
g In Frank Herbert's novel Destination: Void, Tau Ceti is the destination of the ship, precisely because it was known to have no habitable planets. The planet terraformed by the Ship around Tau Ceti may or may not be the setting of the Pandora Series of novels by Frank Herbert and Bill Ransom (The Jesus Incident, The Lazarus Effect, and The Ascension Factor).
g In P├ęter Zsoldos' novel trilogy (Return of the Viking, Distant Fire, The last temptation - originally Hungarian editions but later published in many countries around Europe) Tau Ceti is the destination of the first interstellar expedition of humanity. Gregor Man, a geologist is left behind on one of the planets (called Gama / Lalla) of the star and later becomes the king of the city of Avana.
g In the series Hitchhiker's Guide to the Galaxy, there is a world called "Sirius Tau Ceti," settled (or artificially created) by the Sirius Corporation.
g In the Rama trilogy by Arthur C. Clarke and Gentry Lee, Rama travels through space towards Tau Ceti on their final voyage to the tetrahedric node.
g In Michael McCollum's The Sails of Tau Ceti, Earth is approached by a generation ship which left Tau Ceti as the star turned into a supernova.
g In the film version of Barbarella, the decadent city of Sogo is on a planet in the Tau Ceti system.
g In The Powers of Matthew Starr, the planet Quadris is identified as being a planet of Tau Ceti.
g In Gene Roddenberry's Earth: Final Conflict, the warlike Jaridian species is referred to as having its main stronghold at Tau Ceti.
g In the Star Trek: The Next Generation episode "Journey's End", the alien known as The Traveler is said to come from Tau Ceti. This information, however, contradicts the statement made in the episode "Where No One Has Gone Before" that The Traveler came from Tau Alpha C. In “Star Trek: Enterprise” episode “In a Mirror Darkly,” rebel races battle the Terran Empire at this star system in the mirror universe. In "Star Trek" universe, known as Kaferia (according to "Star Trek Star Charts"), which likely means its the origin of the Kaferian apples mentioned in "Star Trek: The Original Series" episode "Where No Man Has Gone Before."
g In the television series Doctor Who Tau Ceti is mentioned at least twice. In The Stones of Blood and Terror of the Zygons the planets Ogros and Zygor are said to orbit Tau Ceti.
g In Alan Moore's Skizz, Interpreter Zhcchz from Tau Ceti crash-lands outside Birmingham.
g In Naoko Takeuchi's Sailor Moon, Master Pharaoh 90, the leader of the enemy group "Death Busters", comes from Tau Ceti.
g In Yukinobu Hoshino's 2001 Nights, Night 4, "Posterity", depicts an embryo space colonization starship on its voyage to planet Ozma in the Tau Ceti system.
g In the MMORPG EVE Online, the Gallentean race is said to be descended from people of French origin from the Tau Ceti system. The "Tau Ceti Federation", a french speaking alliance in EVE Online, have this name from this fact.
g In the Marathon game trilogy, Tau Ceti IV is the location of a human colony, about which the colony ship U.E.S.C. Marathon orbits.
g In the computer game System Shock 2, Tau Ceti V was where the starship Von Braun travelled on its maiden voyage. It was also the source of the invasion on the ship by both the AI SHODAN and the SHODAN-created lifeforms, the Annelids, which evolved into The Many.
g Pete Cooke's 1985 ZX Spectrum computer game Tau Ceti, published by CRL, was set on an airless planet orbiting the star.
g In David Braben's Frontier: Elite II and Frontier: First Encounters, Tau Ceti is orbited by the habitable, Earth-like (and densely populated) world known as Taylor Colony. The system is a member of the Federation. It was first permanent Human colony outside Solar system, and first non-Earth planet with life discovered.
g In Sid Meier's Alien Crossfire, the vaguely referenced "Tau Ceti flowering" had accidentally destroyed all sentient life in the Tau Ceti system. This destruction is the primary argument used by the alien Progenitor Manifold Caretakers against causing further flowerings in other systems.
g In all three of the Escape Velocity games, Tau Ceti is the primary of a major star system.
g In Battletech, Tau Ceti is the first planet traveled to by human beings. This is accomplished by the TAS Pathfinder a ship powered by the Kearny-Fushida drive. Once colonized, it is named "New Earth."
g In "Earth and Beyond" series, the Tau Ceti system has been colonized by the Terrans. It is one of the endpoints of the Somerled Trade Run.
g Mentioned in Frederick Pohl's short story "I Plinglot, Who You?"
g Before war breaks out, Earth sends fifty couples as colonists to Tau Ceti II in Poul Anderson's "Epilogue"
g The system's fourth planet, Marduk, is a "pleasure planet" in Robert Silverberg's "The Man in the Maze"

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