Rigel-Sun Comparison Rigel, also known by its Bayer designation Beta Orionis (β Ori, β Orionis), is the brightest star in the constellation Orion and the sixth brightest star in the night sky, with visual magnitude 0.12. The star as seen from Earth is actually a triple star system, with the primary star (Rigel A) a blue-white supergiant of absolute magnitude −7.84 and around 130,000 times as luminous as the Sun. An Alpha Cygni variable, it pulsates periodically. Visible in small telescopes, Rigel B is itself a spectroscopic binary system, consisting of two main sequence blue-white stars of spectral type B9.

Although Rigel has the Bayer designation "beta", it is almost always brighter than Alpha Orionis (Betelgeuse?). Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.

Spectroscopic estimates of Rigel's distance place its distance between 700 and 900 light-years (210 and 280 pc), while Hipparcos's measurement of its parallax gives a distance of 860 light-years (260 pc), with a margin of error of about 9%.2 It is a blue supergiant, at about 18 solar masses,6 shining with approximately 117,000 times the luminosity of the Sun.4 The interferometer-measured angular diameter of this star, after correction for limb darkening, is 2.75 ± 0.01 mas.17 At its estimated distance, this yields a physical size of about 74 times the radius of the Sun.4 If viewed from a distance of 1 astronomical unit, it would span an angular diameter of 35° and shine at magnitude −38.

As it is both bright and moving through a region of nebulosity, Rigel lights up several dust clouds in its vicinity, most notably the IC 2118 (the Witch Head Nebula). Rigel is also associated with the Orion Nebula, which—while more or less along the same line of sight as the star—is almost twice as far away from Earth. Despite the difference in distance, projecting Rigel's path through space for its expected age brings it close to the nebula. As a result, Rigel is sometimes classified as an outlying member of the Orion OB1 Association, along with many of the other bright stars in that region of the sky; more specifically, it is a member of the Taurus-Orion R1 Association, with the OB1 Association reserved for stars closer to the nebula and more recently formed.

Rigel is a variable supergiant, the variability being caused by stellar pulsations similar to those of Deneb, the prototype of the class of Alpha Cygni pulsating stars. The radial velocity variations of Rigel proves that it simultaneously oscillates in at least 19 non-radial modes.The variability periods range broadly from about 1.2 to 74 days. It is a notable star among other blue supergiant stars in the sense that its pulsations are powered by the nuclear reactions in the hydrogen burning shell.The Rigel system is known to be composed of three stars. A fourth star in the system is sometimes proposed, but it is generally considered that this is a misinterpretation of the main star's variability, which may be caused by physical pulsation of the surface.

Rigel in Space Opera:

  • Empire series? (1945–1952), short story and three novels by Isaac Asimov set early in the history of the Galactic Empire that later dominated his overarching Foundation Series of novels. Rigel?, the name of the star, is assumed by one of its planets in the Empire series. In the first millennium of the Galactic Era, this world's inhabitants developed a robot-based civilization that became so decadent and lazy that the effete Rigellians fell easy victim to the depredations of the warlord Moray.
  • Demon Princes (1964–1981), series of five novels written by Jack Vance?. In Vance's Oikumene universe?, Rigel is one of the three principal centers of human civilization (together with the Earth and Vega), the Rigel Concourse consisting of "twenty-six magnificent planets, most of them not only habitable but salubrious.
  • "The Cage?" (1965; first aired complete in 1988), original pilot episode of Star Trek: The Original Series? written by Gene Roddenberry? and directed by Robert Butler?. Much of the story's footage was repurposed in the two-part episode "The Menagerie?" (1966), written by Roddenberry and directed by Marc Daniels?. Captain Christopher Pike and a landing party from the USS Enterprise are attacked inside an apparently abandoned fortress on Rigel VII? by native Kalar warriors.
  • "Mudd's Women?" (1966), episode of Star Trek: The Original Series written by Gene Roddenberry and directed by Harvey Hart?. The notorious Harcourt Fenton Mudd and three extraordinarily beautiful women are rescued by the USS Enterprise—to the burgeoning distraction of the crew. The Enterprise itself is damaged in the adventure, and limps to the harsh, stormy desert planet Rigel XII?, where unknown to Captain Kirk Mudd secretly cements plans to sell the women to the local miners.
  • "Shore Leave?" (1966), episode of Star Trek: The Original Series written by Theodore Sturgeon? and directed by Robert Sparr?. Back in his salad days, while enjoying youthful indescretions on the resort planet Rigel II?, Dr. McCoy had become well acquainted with a couple of scantily-clad ladies from a cabaret chorus line. Now, years later, on the fantasy-fulfilling "Shore Leave" planet, the alluring pair are physically recreated from his imagination. He also meets a white rabbit—who complains of being late.
  • "Journey to Babel"? (1967), episode of Star Trek: The Original Series written by D. C. Fontana? and directed by Joseph Pevney. Intrigue abounds as an assortment of ambassadors, both real and dissembled, and including the first appearance Mr. Spock's father Sarek, board the USS Enterprise en route to negotiations on the neutral planetoid Babel. The subject of this diplomatic exercise is controversial: Shall the Coridan? system, a prime but hotly contested natural source of dilithium crystals, be admitted to the Federation? The Rigelians of Rigel V? (similar in physiology to the Vulcans but possessed of four or five genders) also want to join, and they finally become members in 2184.
  • "Wolf in the Fold?" (1967), episode of Star Trek: The Original Series written by Robert Bloch? and directed by Joseph Pevney?. "Scotty" (Chief Engineer Scott) is accused of the brutal murder of several female acquaintances on the planet Argelius II?—killings actually carried out by an enigmatic and misogynistic entity that has cut an ancient and bloody swath across the galaxy, appearing variously through history as Jack the Ripper on the Earth, and as the woman-killer "Beratis" on the planet Rigel IV?.
  • "The Passenger?" (1993), episode of Star Trek: Deep Space Nine? written by Morgan Gendel? et al and directed by Paul Lynch?. During the 2360s, Kobliad fugitive Rao Vantika used a subspace shunt to access and purge everything in the active memory of computer systems on Rigel VII?. In the "Passenger" episode he seizes mind control of one of the Deep Space 9? regulars and attempts the same method of attack on the station itself.
  • "All Good Things...?" (1994), episode of Star Trek: The Next Generation? written by Brannon Braga? and Ronald D. Moore?, and directed by Winrich Kolbe. Through the machinations of the capricious super-being Q, Captain Picard finds his subjective present jumping between now, 25 years ago, and 25 years from now. In his "ago" state, the USS Enterprise had just been joined by Lt. Geordi La Forge, who "now" has retired, become a novelist, and lives with the wife and kids on Rigel III?.
  • "The Wire?" (1994), episode of Star Trek: Deep Space Nine written by Robert Hewitt Wolfe? and directed by Kim Friedman?. The regular series character and alien Garak is revealed to be a former member of the Obsidian Order, the much-feared Cardassian? intelligence service, when the interrogation-resisting implant in his brain begins to fail. Meanwhile, Keiko O'Brien—the wife of the station's Chief Operations Officer Miles O'Brien—attends a week-long hydroponics conference on the planet Rigel IV?.
  • "Broken Bow?" (2001), pilot episode of Star Trek: Enterprise? written by Rick Berman? and Brannon Braga?, and directed by James Conway?. The Klingon? courier spy Klaang is pursued across the galaxy by Jonathan Archer and the crew of the Enterprise NX-01, and the pursuit passes through Rigel Colony—a 36-level trade complex populated by numerous sentient species, huge houseflies, and gorgeous butterflies—on the ice planet Rigel X?. In the bookend final episode of the series, "These Are the Voyages...?" (2005), written by Berman and Braga, directed by Allan Kroeker?, and fashioned as a prequel lead-in to Star Trek: The Original Series, Rigel X (the original 36-level sets were re-used) is the final world visited by Captain Jonathan Archer and the Enterprise before its decommissioning.
  • In the Escape Velocity game by Ambrosia Software the planet of New Britain is in the system

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