Betelgeuse (Alpha (α) Orionis) is a semiregular variable star located 427 light-years away.^[1] It is the second brightest star in the constellation Orion, and the ninth brightest star in the night sky. Although it has the Bayer designation "alpha", it is not as bright as Rigel (Beta Orionis). It is a vertex of the Winter Triangle asterism. Image File history File links Download high-resolution version (950x950, 35 KB) This is the first direct image of a star other than the Sun. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... It has been suggested that this article or section be merged into Julian epoch. ... This article or section does not adequately cite its references or sources. ... Orion (IPA: ), a constellation often referred to as The Hunter, is a prominent constellation, one of the largest and perhaps the best-known and most conspicuous in the sky. ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (abbrev. ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... Most stars are of almost constant luminosity. ... Illustration of the use of optical wavelength interferometry to determine precise positions of stars. ... Radial velocity is the velocity of an object in the direction of the line of sight. ... kilometre per second is an SI derived unit of both speed (scalar) and velocity (vector), signified by the symbol km/s or km s-1. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... This does not adequately cite its references or sources. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... Distance is a numerical description of how far apart objects are at any given moment in time. ... A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in vacuum in one year. ... A parsec is the distance from the Earth to an astronomical object which has a parallax angle of one arcsecond. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... In astronomy, the solar mass is a unit of mass used to express the mass of stars and larger objects such as galaxies. ... Circle illustration In classical geometry, a radius (plural: radii) of a circle or sphere is any line segment from its center to its boundary. ... In astronomy, the solar radius is a unit of length used to express the size of stars and larger objects such as galaxies. ... Luminosity has different meanings in several different fields of science. ... The solar luminosity, , is a unit of luminosity (power emitted in the form of photons) conventionally used by astronomers to give the luminosities of stars. ... Fig. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... STAR is an acronym for: Organizations Society of Ticket Agents and Retailers], the self-regulatory body for the entertainment ticket industry in the UK. Society for Telescopy, Astronomy, and Radio, a non-profit New Jersey astronomy club. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... Smithsonian Astrophysical Observatory Star Catalog contain the 258,996 stars. ... The Hipparcos and Tycho Catalogues (Tycho-1) are the primary products of the European Space Agencys astrometric mission, Hipparcos. ... SIMBAD (the Set of Identifications, Measurements, and Bibliography for Astronomical Data) is a database of astronomical information about objects within the Milky Way. ... Alpha (uppercase Α, lowercase α) is the first letter of the Greek alphabet. ... Semiregular variable stars are giants or supergiants of intermediate and late spectral type showing considerable periodicity in their light changes, accompanied or sometimes interrupted by various irregularities. ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... STAR is an acronym for: Organizations Society of Ticket Agents and Retailers], the self-regulatory body for the entertainment ticket industry in the UK. Society for Telescopy, Astronomy, and Radio, a non-profit New Jersey astronomy club. ... This article or section does not adequately cite its references or sources. ... Orion (IPA: ), a constellation often referred to as The Hunter, is a prominent constellation, one of the largest and perhaps the best-known and most conspicuous in the sky. ... Bright stars can be bright because they produce more light, because they are closer to us, or both. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... Rigel (pronounced ) (β Orionis) is the brightest star in the constellation Orion and the seventh brightest star in the sky, with visual magnitude 0. ... In geometry, a vertex (plural vertices) is a special kind of point, usually a corner of a polygon, polyhedron, or higher dimensional polytope. ... The Winter Triangle is an astronomical asterism involving an imaginary triangle drawn, during the winter, upon the northern hemispheres celestial sphere; with its defining vertices at Betelgeuse, Procyon, and Sirius. ...

Betelgeuse is a red supergiant, one of the largest stars known. If it were placed at the center of our solar system, its outer surface would extend between the orbit of Mars and Jupiter. As it is, Betelgeuse is so large and so close that it is the star with the third largest angular diameter as viewed from Earth,^[2] smaller only than the Sun and R Doradus, and one of only a dozen or so stars that telescopes have imaged as a visible disk (See photo, at right and a picture of hotspots on Betelgeuse.) The angular diameter of Betelgeuse was first measured in 1920–1921 by Michelson and Pease using an astronomical interferometer on the Mount Wilson 100 inch telescope. Betelgeuse, viewed from a distance of 8 AU. By comparison, this is our own Sun, and how it would appear when viewed from the same distance. ... Below is a list of the largest known stars, by solar diameter. ... Major features of the Solar System (not to scale; from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth and its Moon, and Mars. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Adjectives: Jovian Atmosphere Surface pressure: 20–200 kPa[4] (cloud layer) Composition: ~86% Molecular hydrogen ~13% Helium 0. ... The angular diameter of an object as seen from a given position is the diameter measured as an angle. ... R Doradus is the name for a supergiant star in the constellation Dorado. ... His signature. ... Francis Gladheim Pease (1881–February 7, 1938) was an American astronomer. ... Diagram showing a possible layout for an astronomical interferometer, with the mirrors laid out in a parabolic arrangement (similar to the shape of a conventional telescope mirror). ... The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California. ... A telescope (from the Greek tele = far and skopein = to look or see; teleskopos = far-seeing) is an instrument designed for the observation of remote objects. ...

Origin of the name "Betelgeuse"

The name is a corruption of the Arabic يد الجوزاء yad al-jawzā, or "hand of the central one". The name Betelgeuse also means House of the Twins. Jauza, the central one, initially referred to Gemini among the Arabs, but later referred to Orion instead. During the Middle Ages the first character of the name, y (ﻴ, with two dots under it), was misread as a b (ﺒ, with one dot under it) when transliterating into Latin, and Yad al-Jauza became Bedalgeuze. Then, during the Renaissance, it was theorized that the name was originally written as Bait al-Jauza, thought to mean "armpit of the central one" in Arabic, which led to the modern rendering as "Betelgeuse"; however, the actual translation of "armpit" would be ابط ("Ibţ"). Arabic ( or just ) is the largest living member of the Semitic language family in terms of speakers. ... Gemini (IPA: , Latin: , symbol , ) is one of the constellations of the zodiac known as the twins . It is part of the winter sky, lying between Taurus to the west and the dim Cancer to the east, with Auriga and the near-invisible Lynx to the north and Monoceros and Canis... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... The Renaissance (French for rebirth, or Rinascimento in Italian), was a cultural movement in Italy (and in Europe in general) that began in the late Middle Ages, and spanned roughly the 14th through the 17th century. ...

Because of its rich reddish color the star has frequently been referred to as the "martial one", and in astrology portends military or civic honors. Other names are: Hand-coloured version of the anonymous Flammarion woodcut. ...

• Al Dhira (the Arm),
• Al Mankib (the Shoulder)
• Al Yad al Yamma (the Right Hand)
• Ardra (Hindi, and name of Hindu Nakshatra),
• Bahu (Sanskrit),
• Bašn (Persian) (the Arm),
• Gula (Euphratean),
• Ied Algeuze (Orion's Hand),
• Klaria (Coptic) (an Armlet)
• Yedelgeuse

It is known as 参宿四 (Shēnsùsì, the Fourth Star of the Constellation of Three Stars) in Chinese. The confusing name is due to the fact that the Constellation of Three Stars was originally composed of just three stars, all of them in the girdle of the Orion. Later, four more stars were added to this constellation, but the name remained unchanged. Hindi (Devanagari: or , IAST: , IPA: ), an Indo-European language spoken mainly in northern and central India, is one of the official languages of the Union government of India. ... This article discusses the adherents of Hinduism. ... A nakshatra (Devanagari: नक्षत्र) or lunar mansion is one of the 27 or 28 divisions of the sky, identified by the prominent star(s) in them, that the Moon passes through during its monthly cycle, as used in Hindu astronomy and astrology. ... Sanskrit ( , for short ) is a classical language of India, a liturgical language of Hinduism, Buddhism, and Jainism, and one of the 23 official languages of India. ... Persian (Local names: فارسی Fârsi or پارسی Pârsi)* is an Indo-European language spoken in Iran, Afghanistan and Tajikistan as well as by minorities in Uzbekistan, Turkmenistan, India, Pakistan, Azerbaijan, Georgia, Southern Russia, neighboring countries, and elsewhere. ... Surfer Rosa The Euphrates (IPA: /juːˈfreɪtiːz/; Greek: EuphrátÄ“s; Akkadian: Pu-rat-tu; Hebrew: פְּרָת PÄ•rāth; Syriac: Prâth; Arabic: الفرات Al-Furāt; Turkish: Fırat; Kurdish: فرهات, Firhat, Ferhat, Azeri: FÉ™rat) is the western of the two great rivers that define Mesopotamia (the other... This article or section is not written in the formal tone expected of an encyclopedia article. ...

Distinguishing characteristics

Several features of Betelgeuse are of particular interest to astronomers. It was one of the first stars to have its angular diameter measured with an astronomical interferometer; the apparent diameter was found to be variable. The distance to Betelgeuse is not precisely known, but if it is assumed to be 427 light years then the actual diameter varies between 500 and 800 times the Sun's diameter. It has a color index (B-V) of 1.86. It is thought to have a mass of about 14 solar masses. Diagram showing a possible layout for an astronomical interferometer, with the mirrors laid out in a parabolic arrangement (similar to the shape of a conventional telescope mirror). ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ...

The precise diameter is not easy to define, as the optical emission decreases very gradually with radius from the center of the star, and the color of the emission also varies with radius. Though only 14 times more massive than the Sun, it is as much as 300 million times greater in volume; a difference in volume much like a beach ball compared to a large stadium. It was also the first star to have starspots on its disk resolved in optical images by a telescope, first from Aperture Masking Interferometry and later from more detailed observations by the COAST telescope. A beach ball is a large inflatable ball used in various games and other recreational activities traditionally conducted on the beach. ... Telstra Stadium in Sydney, Australia is capable of being converted from a rectangular rugby football field to an oval for cricket and Australian rules football games This article is about the building type. ... a) shows a simple experiment using an aperture mask in a re-imaged aperture plane. ...

Betelgeuse (↑) in Orion

Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ...

The star's future

Astronomers predict that Betelgeuse will ultimately undergo a type II supernova explosion although it is possible that the mass is low enough for Betelgeuse to leave a rare oxygen-neon white dwarf. Opinions are divided as to the likely timescale for this event. Although Betelgeuse is only around 10 million years old, some regard the star's current variability as suggesting that it is already in the carbon burning phase of its life cycle, and will therefore undergo a supernova explosion at some time in the next thousand years or so. Skeptics dispute this contention and regard the star as being likely to survive much longer. There is a consensus that such a supernova would be a spectacular astronomical event, but would not — being so distant — represent any significant threat to life on Earth. Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Standard atomic weight 20. ... This article or section does not adequately cite its references or sources. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ...

Even so, Betelgeuse would brighten at least 10,000 times as a supernova, causing it to shine with the luminosity of a crescent Moon. Some sources predict a maximum apparent magnitude equal to about that of the full Moon (mv = -12.5). This would likely last for several months. It would look like a brilliant point, the brightness of a full Moon with the color of an incandescent bulb at night, and easily visible in daylight. After that period it would gradually diminish until after some months or years it would disappear from naked eye view. Then Orion's right shoulder would vanish for a time until, in a few centuries, a splendid nebula would develop. However, if Betelgeuse's axis (one of its poles) is pointed towards Earth there would be tangible effects here. A shower of gamma rays and other cosmic particles would be directed at Earth. There would be spectacular aurorae and possibly a measurable diminution of the ozone layer with consequent adverse radiation effects on life. In such an orientation towards the solar system it would also appear many times brighter than if its axis were pointed away. The Triangulum Emission Nebula NGC 604 The Pillars of Creation from the Eagle Nebula For other uses, see Nebula (disambiguation). ... Aurora borealis Aurora borealis The aurora is a glow observed in the night sky, usually in the polar zone. ... The ozone layer is the part of the Earths atmosphere which contains relatively high concentrations of ozone (O3). ... Major features of the Solar System (not to scale; from left to right): Pluto, Neptune, Uranus, Saturn, Jupiter, the asteroid belt, the Sun, Mercury, Venus, Earth and its Moon, and Mars. ...

Curiously, in 1980, Shu-ren, Jianmin and Jin-Yi unearthed 1st century BC Chinese records that refer to the color of Betelgeuse as being white or yellow. However, Ptolemy writing in 150 AD calls it a red star. Therefore, Fang Lizhi, a Chinese astrophysicist, proposed that Betelgeuse could have turned into a red giant star during that period. It is known that as stars use up the hydrogen fuel in their cores, their color changes from white to yellow to red. Shu-ren et al. suggest that Betelgeuse could have changed its color when it expelled a shell of dust and gas, that, even now, can be seen to be expanding away from it. Thus, if their theory is right, it is unlikely that Betelgeuse will become a supernova any time soon because a star usually stays a red giant for tens of thousands of years. The approximate size of the red supergiant is 5.5 times larger than Earth's orbit itself being 822,788,285 kilometres. Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... Fang Lizhi Chinese: 方励之; Hanyu Pinyin: (born February 12, 1936) was a professor of astrophysics and vice president of the University of Science and Technology of China whose teachings inspired the pro-democracy Tiananmen Square protests of 1989. ...

AAVSO V-band light curve of Betelgeuse, (a.k.a Alpha Orionis) from Dec. 1988 - Aug. 2002

Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The American Association of Variable Star Observers (AAVSO) is an organization that collects observations of variable stars by amateur astronomers and uses them to establish light curves for each stars variation in brightness over time. ... In astronomy, a Photometric system is a set of discrete passbands (of filters), with a known sensitivity to incident radiation. ... In astronomy, a light curve is a graph of light intensity as a function of time. ...

References

• Peter G. Tuthill, Chris A. Haniff, John E. Baldwin, Hotspots on late-type supergiants, Monthly Notices of the Royal Astronomical Society, Volume 285, Issue 3, pp. 529-539 (1997).
• Li-Zhi, Fang, Chinese Astronomy and Astrophysics (an English journal), 1981 or 1982
• "When did it change to red?", The Hindu (a popular English language newspaper in India), Sunday Supplement, January 31-1982.
• Davis, Kate (2000-12-01). Variable Star of the Month—December, 2000: Alpha Orionis (English). AAVSO. Retrieved on 2006-08-13.
• Interferometric observations of the supergiant stars α Orionis and α Herculis with FLUOR at IOTA, February 2004
• Magnetic activity in late-type giant stars: Numerical MHD simulations of non-linear dynamo action in Betelgeuse
• Invisible Giant: Chandra's Limits on X-rays from Betelgeuse

Prof. ... For the Manfred Mann album, see 2006 (album). ... August 13 is the 225th day of the year in the Gregorian calendar (226th in leap years), with 140 days remaining. ...

See also

• Betelgeuse in fiction
• List of largest known stars

Betelgeuse (Alpha Orionis) is a red supergiant star in the constellation Orion that regularly appears or is referenced in science fiction: // Philip K. Dick references Betelgeuse in several novels and short stories. ... Below is a list of the largest known stars, by solar diameter. ...

External links

• ^  Images of hotspots on the surface of Betelgeuse taken at visible and infra-red wavelengths using high resolution ground-based interferometers.
• SIMBAD Query Result for Betelgeuse. SIMBAD international database. Retrieved on 4 April, 2005.
• Betelgeuse. SolStation. Retrieved on 11 November, 2005.