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Betelgeuse

 
Dictionary: Be·tel·geuse   (bēt'l-jūz', bĕt'l-jœz') pronunciation
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n.
A bright-red intrinsic variable star, 527 light-years from Earth, in the constellation Orion.

[French Bételgeuse, ultimately from Arabic yad al-jawzā' : yad, hand + al-, the + jawzā', Gemini (later also used for Orion), perhaps akin to jawz, center, middle.]

WORD HISTORY   The history of the curious star name Betelgeuse is a good example of how scholarly errors can creep into language. The story starts with the pre-Islamic Arabic astronomers, who called the star yad al-jawzā', "hand of the jawzā'." The jawzā' was their name for the constellation Gemini. After Greek astronomy became known to the Arabs, the word came to be applied to the constellation Orion as well. Some centuries later, when scribes writing in Medieval Latin tried to render the word, they misread the y as a b (the two corresponding Arabic letters are very similar when used as the first letter in a word), leading to the Medieval Latin form Bedalgeuze. In the Renaissance, another set of scholars trying to figure out the name interpreted the first syllable bed- as being derived from a putative Arabic word *bāṭ meaning "armpit." This word did not exist; it would correctly have been ibṭ. Nonetheless, the error stuck, and the resultant etymologically "improved" spelling Betelgeuse was borrowed into French as Bételgeuse, whence English Betelgeuse.


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Britannica Concise Encyclopedia: Betelgeuse
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(from Arabic bat al-dshauza, "the giant's shoulder") Brightest star in the constellation Orion, marking the hunter's eastern shoulder. About 430 light-years from Earth, Betelgeuse is easily identifiable by its brightness, its position in brilliant Orion, and its deep reddish colour. It is a red supergiant star, one of the largest known; its diameter is roughly 500 times that of the Sun.

For more information on Betelgeuse, visit Britannica.com.

Sci-Tech Encyclopedia: Betelgeuse
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A cool and highly luminous star, prominently located in the right shoulder of the constellation Orion and noticeably red in color. Betelgeuse, or α Orionis, is a supergiant star about 130 parsecs (430 light-years) from the Sun. Its spectral type of M2 indicates an effective temperature of approximately 3500 K (5800°F). This temperature would result in a low overall luminosity were it not for the enormous diameter of the star, about 1100 times that of the Sun. Replacing the Sun, Betelgeuse would fill the solar system to beyond the orbit of Mars. Betelgeuse is a supergiant star with approximately 150,000 times the Sun's luminosity. Its mean density is extremely low, less than one-millionth the density of water, and the low surface gravity of the rarefied outer layers results in a continual loss of matter, presently at the rate of 1 solar mass every 250,000 years. Observations at infrared and radio wavelengths show a complex system of dust and gas shells extending out as far as a few hundred stellar radii. See also Spectral type; Stellar evolution; Supergiant star; Variable star.

Speckle interferometry techniques have also produced the first images of the disk of a star and show asymmetric brightness variations over the surface that change with time and are possibly due to large-scale convection of material within the star's atmosphere. Betelgeuse has also been imaged by the Hubble Space Telescope at ultraviolet wavelengths showing the asymetric inner atmosphere of the star and a central hot spot. See also Speckle; Star.

 
Columbia Encyclopedia: Betelgeuse
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Betelgeuse (bēt'əljūz'), bright star in the constellation Orion; Bayer designation α Orionis; 1992 position R.A. 5h54.8m, Dec. +7°24′. A red supergiant with a luminosity about 13,000 times that of the sun, it is of spectral class M2 Iab. Betelgeuse is a semiregular variable star with apparent magnitude ranging from 0.06 to 0.75; thus, at maximum brightness it is one of the 10 brightest stars in the sky. Betelgeuse marks the right shoulder of Orion; its distance is about 500 light-years.

Wikipedia: Betelgeuse
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This article is about the star. For the film, see Beetlejuice. For the oil tanker, see Betelgeuse incident.
Betelgeuse (α Ori)
Position Alpha Ori.png
The pink arrow at the star on left labeled α indicates Betelgeuse in Orion.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
Pronunciation /ˈbiːtəldʒuːz/ or
/ˈbɛtəldʒuːz/[1]
Right ascension 05h 55m 10.3053s[2]
Declination +07° 24′ 25.426″[2]
Apparent magnitude (V) 0.58[2] (0.3 to 1.2)
Characteristics
Spectral type M2Iab[2]
U-B color index 2.06[2]
B-V color index 1.85[2]
Variable type SR c[2] (Semi-regular)
Astrometry
Radial velocity (Rv) +21.0[2] km/s
Proper motion (μ) RA: 24.95 ± 0.08[3] mas/yr
Dec.: 9.56 ± 0.15[3] mas/yr
Parallax (π) 5.07 ± 1.10[3] mas
Distance 640 ± 140 [3] ly
(197 ± 45 [3] pc)
Absolute magnitude (MV) −5.14
Details
Mass 18-19[4] M☉
Radius 936[5] R☉
Surface gravity (log g) -0.5[6]
Luminosity 105,000[4] L☉
Temperature 3,500[6] K
Age ~10 million[5] years
Other designations

Betelgeuse is a semiregular variable star located approximately 640 light-years from the Earth.[5] It is Alpha Orionis (α Orionis / α Ori), but the second brightest star in the constellation Orion and the ninth brightest star in the night sky. Although Betelgeuse has the Bayer designation α, Rigel (Beta Orionis) is usually brighter (Betelgeuse is a variable star and is on occasion brighter than Rigel). The star is a vertex of the Winter Triangle and center of the Winter Hexagon.

Betelgeuse is a red supergiant, and one of the largest and most luminous stars known. For comparison, if the star were at the center of our solar system its surface might extend out to between the orbits of Mars and Jupiter, wholly engulfing Mercury, Venus, the Earth and Mars. The angular diameter of Betelgeuse was first measured in 1920–1921 by Michelson and Pease using the 100 inch (2.5 m) John D. Hooker astronomical interferometer telescope atop Mount Wilson.

Astronomers believe Betelgeuse is only a few million years old, but has evolved rapidly because of its high mass.[7] Some astronomers believe it may become a supernova within a timeframe where it could be observable by human civilization.

Contents

Etymology

Ambox content.png
 This section's factual accuracy is disputed. Please see the relevant discussion on the talk page. (August 2009)

The proper name for this star, Betelgeuse is also spelled Betelgeux,[1] Beteigeuze[8] in German (according to Bode[9][10]) and so on. There are multiple sources with competing etymologies for the star's name. All agree that the last part of the name "-elgeuse" comes from Arabic الجوزاء al-Jauzā', the indigenous Arabic name for the constellation Orion, a feminine name in old Arabian legend, and of uncertain meaning. جوز j-w-z, the root of jauzā' means "middle". Because al-Jauzā' roughly means "the Central One". Later confusingly, al-Jauzā' was also designated as scientific Arabic name for Orion and Gemini. The current Arabic name for Orion is الجبار al-Jabbār ("the Giant"), though the use of الجوزاء al-Jauzā' in the name of the star has continued.

One hypothesis is that the full name is a corruption of the Arabic يد الجوزاء Yad al-Jauzā' meaning "the Hand of al-Jauzā', i.e. Orion". European mistransliteration into Latin during the Middle Ages led to the first character y (ﻴ, with two dots underneath) being misread as a b (ﺒ, with only one dot underneath). During the Renaissance the star's name was written as بيت الجوزاء Bait al-Jauzā' ("house of Orion") or بط الجوزاء Baţ al-Jauzā' incorrectly thought to mean "armpit of Orion" (a true translation of "armpit" would be ابط, transliterated as Ibţ). This led to the modern rendering as Betelgeuse.[11]

A competing explanation coming from Richard Hinckley Allen, who instead saw the origin in ابط الجوزاء Ibṭ al-Jauzah, which he claims degenerated into a number of forms including Bed Elgueze, Beit Algueze, and Bet El-gueze[12].

An alternative name for this star in Arabic was منكب الجوزاء Mankib al Jauzā' or "the Shoulder of Orion". In Persian however, the name is اِبطالجوزا, derived from the Arabic ابط الجوزاء Ibţ al-Jauzā', "armpit of Orion".

Recommended pronunciations for "Betelgeuse" are as varied as its spellings. The Royal Astronomical Society of Canada favors 'bɛtəldʒuːz ("BET-l-jooz"), while The Friendly Stars has ˈbɛtəldʒəz ("BET-l-jz").[13] Websters Collegiate Dictionary suggests both 'bɛtəldʒuːz ("BET-l-jooz") and 'bɛtəldʒjuːz ("BET-l-jeuz"), while popular culture, in such forms as the Tim Burton film Beetlejuice and The Hitchhiker's Guide to the Galaxy, pronounces it biːtəldʒjuːs, or "Beetle-juice".[13]

Because of its rich reddish color the star has also been called "the martial one"[citation needed] and in astrology Betelgeuse portends military or civic honors.[citation needed]

This bright star has had many other names:

In traditional Chinese astronomy, Betelgeuse was known as 参宿四 (Shēnxiùsì, the Fourth (Star of the constellation) of Three (Stars)) because the Chinese constellation of 参宿 was at first a name for only three stars in the girdle of the Orion. Four more stars were later added to this constellation but the earlier name stuck.

In Japan, this star was called Heike-boshi (suggestion from the red-butterfly flag of Heike clan), (平家星)[14][15], "the Star of Heike clan" or Kin-waki, (金脇), "the Gold (Star) beside (Mitsu-boshi)."

Observation

Betelgeuse's variability in brightness was first described by Sir John Herschel in 1836 when he published his observations of the star in Outlines of Astronomy, noting the variations increased between 1836 and 1840, then decreased again. In 1849, he noted a shorter cycle of variability which peaked in 1852. Later observers recorded unusually high maxima with an interval of several years but only small variations between 1957 and 1967. Records of the American Association of Variable Star Observers show maximum brightnesses of magnitude 0.2 in 1933 and 1942, with minimums below magnitude 1.2 in 1927 and 1941.[16]

In 1919, Albert Michelson and Francis Pease mounted a 6 metre (20 ft) interferometer on the front of the 2.5 metre (100 inch) telescope at Mount Wilson Observatory. Helped by John A. Anderson, in December 1920 Pease measured the angular diameter of α Orionis as 0.047 arcseconds. Given the then-current parallax value of 0.018 arcseconds, this resulted in an estimated radius of 3.84 × 108 km (240 million miles). However there was known uncertainty owing to limb darkening and measurement errors.[17][18] More recent visible-light observations of Betelgeuse have found the diameter to vary between 0.0568 and 0.0592 arcseconds.

In the late 1980s and early 1990s, Betelgeuse became a regular target for Aperture Masking Interferometry visible-light and infrared imaging, revealing a number of bright spots on the star's surface, which were thought to result from convection.[19]. These were the first optical and infrared images of the disk of a star other than our Sun and generally showed one or more bright patches indicating the location of hotspots in the stellar photosphere. In 1995, the Faint Object Camera on the Hubble Space Telescope was used to capture an ultraviolet image with comparable resolution—this was the first conventional-telescope image (or "direct-image" in NASA terminology) of the disk of another star. The image was made at ultraviolet wavelengths as at ultraviolet wavelengths ground-based instruments cannot produce images with resolution as high as Hubble. Like earlier images, this ultraviolet image also had a bright patch indicating a higher temperature region, in this case on the southwestern portion of the star's surface. Visual observation have shown Betelgeuse's rotation axis has an inclination of about 20° to the direction of Earth and a position (or height) angle of about 55°. Hence, it was hypothesized that the hot spot seen in the ultraviolet image could be one of the star's poles.[20]

Recent ground-based infrared measurements of the disk of Betelgeuse gave a mid-infrared angular diameter of 54.7 ± 0.3 milli-arcseconds in November 1999, slightly smaller than the typical visible-light angular diameter. These measurements ignored any possible contribution from hotspots (which are less-noticeable in the mid-infrared) but factored-in some limb darkening, whereby the intensity of a star's image diminishes near the edge, as the photospheric gas gets thinner. It is difficult to define the precise diameter of Betelgeuse as the photosphere has no "edge"—instead the gas making up the photosphere gets gradually thinner with distance from the star.[21]

In July 2009, images released by European Southern Observatory, taken by the ground based Very Large Telescope, gave a more detailed view of the surface of the star[22]. In the picture a plume of gas is seen extending from the star. This plume extends six times the diameter of Betelgeuse itself[23]. This is comparable to the distance between the Sun and Neptune.

Observed size

Betelgeuse imaged in ultraviolet light by the Hubble Space Telescope and subsequently enhanced by NASA. The bright white spot is likely one of its poles. NASA/ESA credit.[24][25]
AAVSO V-band light curve of Betelgeuse (Alpha Orionis) from Dec. 1988 - Aug. 2002

Betelgeuse has several features which are of particular interest to astronomers. Because of the size and proximity of this star it has the third largest angular diameter as viewed from Earth,[26] smaller only than the Sun and R Doradus. Moreover, it is one of only a dozen or so stars telescopes have imaged as a visible disk. The angular diameter of Betelgeuse was one of the first to be measured with an astronomical interferometer and the apparent diameter was found to be variable. The distance to Betelgeuse is not known precisely. "Direct parallax measures from space, using the most modern results, give 495 light years, whereas the parallax using the star's natural radio emission gives 640 light years."[4] Assuming a compromise distance of 570 light years, the star's diameter would be about 950 to 1,000 times that of the Sun. Betelgeuse has a color index (B-V) of 1.86 and is thought to have a mass of about 20 solar masses.[4]

The precise diameter is hard to define since optical emissions decrease very gradually with radius from the center of Betelgeuse and the color of these emissions also vary with radius. Though only 20 times more massive than the Sun, this star could be hundreds of millions times greater in volume (as with a beach ball compared to a large stadium). Betelgeuse was the first star on which starspots were resolved in optical images by a telescope, first from ground-based Aperture Masking Interferometry and later from the Hubble Space Telescope, followed by higher-resolution observations by the ground-based COAST telescope.[4][27] Between 1993 and 2009, the star's diameter has contracted by over 15 percent.[28]

Betelgeuse's photosphere has an extended atmosphere which displays strong lines of emission (rather than absorption). This chromosphere has a temperature no higher than 5,500 K and may stretch outward to 7 times the diameter of the star. This extended gaseous atmosphere has been observed moving both away from and towards Betelgeuse, apparently depending on radial velocity fluctuations in the photosphere.[6]

Fate

It is possible that Betelgeuse will become a supernova,[4][29] which will be the brightest ever recorded, outshining the Moon in the night sky.[29] Considering its size and age of 8.5 million years, old for its size class, it may explode within the next thousand years.[29] Since its rotational axis is not toward the Earth and also because of its 640 light year distance,[29] Betelgeuse's supernova will not cause a gamma ray burst in the direction of Earth large enough to damage its ecosystems.

Nobel Laureate Charles Townes announced evidence that 15 consecutive years of stellar contraction has been observed by UC Berkeley's Infrared Spatial Interferometer (ISI) atop Mt. Wilson Observatory in Southern California. Reported on June 9, 2009, the star has shrunk 15% since 1993 with an increasing rate. The average speed at which the radius of the star is shrinking over the last 15 years is approximately 210–219 m/s (470–490 mph).[30]

According to the university, Betelgeuse's radius is about 5.5 A.U.s, and the star's radius has shrunk by a distance equal to half an astronomical unit, or about the orbit of Venus.[31] Some theorists[who?] have speculated that this behavior is expected for a star at the beginning of the gravitational collapse at the end of its life.[citation needed] The mass of Betelgeuse puts it in range to become a neutron star or possibly a black hole.

See also

References

  1. ^ a b Burchfield, R. W., (ed.). (1972) A Supplement to the Oxford English Dictionary, vol. 1・A-G, Claredon Press, Oxford, p.249.
  2. ^ a b c d e f g h i "SIMBAD query result: V* alf Ori -- Semi-regular pulsating Star". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=betelgeuse. Retrieved 2007-06-20. 
  3. ^ a b c d e (5), Table 6, A New VLA-Hipparcos Distance to Betelgeuse and its Implications, Graham M. Harper, Alexander Brown, and Edward F. Guinan, The Astronomical Journal 135, #4 (April 2008), pp. 1430–1440, Bibcode: 2008AJ....135.1430H, doi:10.1088/0004-6256/135/4/1430.
  4. ^ a b c d e f astro.uiuc.edu, Betelgeuse (Alpha Orionis) - Update 2008, Stars, Jim Kaler, retrieved 9 October 2008.
  5. ^ a b c Professor James B. (Jim) Kaler. "Betelgeuse (Alpha Orionis)". University of Illinois. http://www.astro.illinois.edu/~jkaler/sow/betelgeuse.html. Retrieved 2009-07-19. 
  6. ^ a b c Lobel, A.; Dupree, A. K. (2000). "Modeling the Variable Chromosphere of α Orionis". The Astrophysical Journal 545: 454–74. doi:10.1086/317784. http://www.journals.uchicago.edu/doi/full/10.1086/317784. Retrieved 2007-02-04. 
  7. ^ "Betelgeuse". SolStation. http://www.solstation.com/x-objects/betelgeuse.htm. Retrieved 2005-11-11. 
  8. ^ Likely the result of mistaking the l for an i. Ultimately, this led to the modern Betelgeuse.
  9. ^ Bode, J. E., (ed.). (1782) Vorstellung der Gestirne: auf XXXIV Kupfertafeln nach der Parisier Ausgabe des Flamsteadschen Himmelsatlas, Gottlieb August Lange, Berlin / Stralsund, pl. XXIV.
  10. ^ Bode, J. E., (ed.) (1801). Uranographia: sive Astrorum Descriptio, Fridericus de Harn, Berlin, pl. XII.
  11. ^ Kunitzsch, P., & Smart, T., (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, MA: Sky Pub. p. 45. ISBN 9781931559447. 
  12. ^ a b c d e f g h Allen, R. H., (1963). Star Names: Their Lore and Meaning (rep. ed.). New York, NY: Dover Publications Inc.. p. 310. ISBN 0486210790. 
  13. ^ a b Jeff Kanipe (2005). "SpaceWatch -- A Star by Any Other Name". http://www.space.com/spacewatch/spacewatch_001214.html. Retrieved 2009-10-23. 
  14. ^ "Daijirin" p.815 ISBN：4385139024
  15. ^ Hōei Nojiri"Shin seiza jyunrei"p.19 ISBN： 9784122041288
  16. ^ Burnham, Robert (1978). Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System, Volume 2. New York: Courier Dover Publications. pp. 1290. ISBN 0486235688. 
  17. ^ Michelson AA, Pease FG. (1921). "Measurement of the diameter of alpha Orionis with the interferometer". Astrophysical Journal 53: 249–59. doi:10.1086/142603. http://adsabs.harvard.edu/abs/1921ApJ....53..249M. Retrieved 2007-06-20. 
  18. ^ Staff (November 2000). "Pease, Francis G (1881–1938)". Encyclopedia of Astronomy and Astrophysics. http://eaa.crcpress.com/default.asp?action=summary&articleId=3915. Retrieved 2007-06-20. 
  19. ^ D. Buscher et al. (1990). "Detection of a bright feature on the surface of Betelgeuse". Monthly Notices of the Royal Astronomical Society 245: 7. http://adsabs.harvard.edu/cgi-bin/bib_query?1990MNRAS.245p...7B. Retrieved 2007-08-07.  R. Wilson et al. (1997). "The changing face of Betelgeuse". Monthly Notices of the Royal Astronomical Society 291: 819. http://adsabs.harvard.edu/cgi-bin/bib_query?1997MNRAS.291..819W. Retrieved 2007-08-07. 
  20. ^ Uitenbroek H, Dupree AK, Gilliland RL (1998). "Spatially Resolved Hubble Space Telescope Spectra of the Chromosphere of α Orionis". The Astronomical Journal 116: 2501–12. http://www.iop.org/EJ/article/1538-3881/116/5/2501/980184.html. Retrieved 2007-06-20. 
  21. ^ Weiner J et al. (2000). "Precision Measurements of the Diameters of α Orionis and ο Ceti at 11 Microns". The Astrophysical Journal 544 (2): 1097–1100. doi:10.1086/317264. http://www.journals.uchicago.edu/doi/full/10.1086/317264. Retrieved 2007-06-23. 
  22. ^ http://www.eso.org/public/outreach/press-rel/pr-2009/pr-27-09.html
  23. ^ The close circumstellar environment of Betelgeuse - Adaptive optics spectro-imaging in the near-IR with VLT/NACO. http://arxiv.org/abs/0907.1843. 
  24. ^ The yellow/red "image" or "photo" of Betelgeuse usually seen is actually not a picture of the red giant but rather a mathematically generated image based on the photograph. The photograph was actually of much lower resolution: The entire Betelgeuse image fit entirely within a 10x10 pixel area on the Hubble Space Telescopes Faint Object Camera. The actual images were oversampled by a factor of 5 with bicubic spline interpolation, then deconvolved.
  25. ^ Gilliland, Ronald; L.; Dupree, A. K.. "First Image of the Surface of a Star with the Hubble Space Telescope". Astrophysical Journal Letters v.463, p.L29. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1996ApJ...463L..29G. 
  26. ^ Bedding TR, et al. (1997). "The angular diameter of R Doradus: a nearby Mira-like star". Monthly Notices of the Royal Astronomical Society 286 (4): 957–62. http://adsabs.harvard.edu/abs/1997astro.ph..1021B. Retrieved 2007-06-20. 
  27. ^ Burns D, et al. (1997). "The surface structure and limb-darkening profile of Betelgeuse". Monthly Notices of the Royal Astronomical Society 290 (1): L11–L16. 
  28. ^ Ron Cowen (2009-06-10). "Betelgeuse shrinks: The red supergiant has lost 15 percent of its size". http://www.sciencenews.org/view/generic/id/44573/title/Betelgeuse_shrinks.  "The shrinkage corresponds to the star contracting by a distance equal to that between Venus and the sun, researchers reported June 9 at an American Astronomical Society meeting and in the June 1 Astrophysical Journal Letters."
  29. ^ a b c d Betelgeuse could explode as a supernova » Radio Podcasts | Earth & Sky
  30. ^ http://esciencenews.com/articles/2009/06/09/red.giant.star.betelgeuse.mysteriously.shrinking
  31. ^ http://www.berkeley.edu/news/media/releases/2009/06/09_betelim.shtml

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v • d • e
Stars of Orion
π3 • π2 • π4 • ο1 • 5 • 6 • π1 • π5 • ο2 • π6 • 11 • 12 • 13 • 14 • 15 • 16 • ρ • 18 • β (Rigel) • 20 • 21 • 22 • 23 • γ (Bellatrix) • 25 • 26 • 27 • η (Algjebba) • 29 • ψ • 31 • 32 • 33 • δ (Mintaka) • 35 • 36 • φ1 (Khad) • 38 • λ (Meissa) • φ2 • θ1 (Trapezium Cluster) • 42 • θ2 • ι (Hatsya) • 45 • ε (Alnilam) • ω • 48 • 49 • ζ (Alnitak) • 51 • 52 • κ (Saiph) • χ1 • 55 • 56 • 57 • α (Betelgeuse) • 59 • 60 • μ • χ2 • 63 • 64 • 65 • 66 • ν • 68 • 69 • ξ • 71 • 72 • 73 • 74 • 75
List

Coordinates: Sky map 05h 55m 10.3053s, +07° 24′ 25.426″


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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
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