Rigel
| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Orion |
| Pronunciation | /ˈraɪdʒəl, -gəl/[1] |
| Right ascension | 05h 14m 32.27210s[2] |
| Declination | −08° 12′ 05.8981″[2] |
| Apparent magnitude (V) | 0.12[3] |
| Characteristics | |
| Spectral type | B8 Iae:[4] |
| U−B color index | −0.66[3] |
| B−V color index | −0.03[3] |
| Variable type | Slightly irregular |
| Astrometry | |
| Radial velocity (Rv) | 20.7[5] km/s |
| Proper motion (μ) | RA: +1.31[2] mas/yr Dec.: +0.50[2] mas/yr |
| Parallax (π) | 3.78 ± 0.34[2] mas |
| Distance | 860 ± 80 ly (260 ± 20 pc) |
| Absolute magnitude (MV) | –7.84 ± 0.2[4] |
| Details | |
| Mass | 24 ± 3[4] M☉ |
| Radius | 71[6] R☉ |
| Luminosity | 66,000(bolometric)[citation needed] L☉ |
| Surface gravity (log g) | 1.75 ± 0.10[4] |
| Temperature | 12,130[7] K |
| Metallicity [Fe/H] | –0.06 ± 0.10[4] dex |
| Rotational velocity (v sin i) | 40[8] km/s |
| Age | (8 ± 1) × 106[4] years |
| Other designations | |
| Database references | |
| SIMBAD | data |
Rigel (β Ori, β Orionis, Beta Orionis) is the brightest star in the constellation Orion and the sixth brightest star in the sky, with visual magnitude 0.18. Although it 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.[10]
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[edit] Physical properties
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 24 solar masses,[4] shining with approximately 85,000 times the luminosity of the Sun.[11] The interferometer-measured angular diameter of this star, after correction for limb darkening, is 2.55 ± 0.05 mas.[12] At its estimated distance, this yields a physical size of about 71 times the radius of the Sun.[6]
Rigel is the most luminous star in our local region of the Milky Way; the nearest more powerful star is Naos, almost 1,100 light years away in Puppis. If viewed from a distance of 1 astronomical unit, it would span an angular diameter of 35° and shine at magnitude −38. The power flux is 100 MW / m2 or 10 kW / cm2, compared to the Sun's flux of 1.4 kW / m2. The power flux at this distance is the same as the flux a few millimeters from a welding arc; any object this close would be vaporized and blown away by the strong stellar wind.[original research?]
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).[13] 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.[13]
Rigel is variable, in an irregular way common to supergiants, with a range from 0.03 to 0.3 of a magnitude over roughly 22 to 25 days. 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.[14]
[edit] Spectroscopy
Rigel is surrounded by a shell of expelled gas. This occurs because when a red giant becomes a blue giant, the slow stellar winds of the former red giant are pressed against by the faster winds of the blue giant, therefore creating a shell.[13]
[edit] System
Rigel has been a known visual binary since at least 1831, when it was first measured by F. G. W. Struve. Though Rigel B is not particularly faint at magnitude 6.7, its closeness to Rigel A—which is over 500 times brighter—makes it a challenging target for telescopes smaller than 150 mm (5.9 in).[14] However a good 7 cm telescope will reveal Rigel B at 150x power and good seeing. At Rigel's estimated distance, Rigel B is separated from its primary by over 2200 AU; not surprisingly, there has been no sign of orbital movement, though they share the same proper motion.[13][14]
Rigel B is itself a spectroscopic binary system, consisting of two main sequence stars that orbit their center of gravity every 9.8 days. The stars both belong to the spectral class B9V; Rigel B is the more massive of the pair, at 2.5 versus 1.9 solar masses.[13][14]
There was long-running controversy in the late 19th and early 20th century over the possible visible binarity of Rigel B. A number of experienced observers claimed to see it as a double, while others were unable to confirm it; indeed, the proponents themselves were sometimes unable to duplicate their results. Observations since have ruled out the likelihood of a visible companion to Rigel B.[13][14]
[edit] Etymology and cultural significance
The star's name comes from its location at the "left foot" of Orion. It is a contraction of Riǧl Ǧawza al-Yusra, this being Arabic for left foot of the central one.[1] Another Arabic name is رجل الجبار riǧl al-ǧabbār, the foot of the great one (giant, conqueror, etc.), which is also the source of the rarely-used variant names Algebar or Elgebar.
It is known as 参宿七 (Shēnxiù Qī, "The Seventh of the Three Stars") in Chinese. The name is because the Asterism 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 asterism, but the name remained unchanged.
In Japan, this star was called Genji-boshi (源氏星) (suggestion from the white flag of Genji clan),[15][16] "the Star of Genji clan" or Gin-waki, (銀脇), "the Silver (Star) beside (Mitsu-boshi)."
In stellar navigation, Rigel is one of the most important navigation stars, since it is bright, easily located and equatorial, which means it is visible all around the world's oceans.
Rigel was known as Yerrerdet-kurrk to the Wotjobaluk koori of southeastern Australia, and held to be the mother-in-law of Totyerguil (Altair). The distance between them signified the taboo preventing a man from approaching his mother-in-law.[17]
In ancient Egypt Rigel's name was
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Seba-en-Sah Sb3-n-S3ḥ, which means toe star or foot star.
The Maori people named Rigel as Puanga and was said to be a daughter of Rehua (Antares), the chief of all stars.[18]
[edit] See also
- List of largest known stars
- Blue supergiant
- List of most luminous stars
- List of brightest stars
- List of most massive stars
- Rigel in fiction
[edit] Notes
- ^ a b "Define Rigel at Dictionary.com". http://dictionary.reference.com/browse/rigel. Retrieved 6 February 2012.
- ^ a b c d e f van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. Bibcode 2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- ^ a b c Nicolet, B. (1978). "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System". Astronomy and Astrophysics Supplement Series 34: 1–49. Bibcode 1978A&AS...34....1N.
- ^ a b c d e f g Przybilla, N. et al (January 2006). "Quantitative spectroscopy of BA-type supergiants". Astronomy and Astrophysics 445 (3): 1099–1126. Bibcode 2006A&A...445.1099P. doi:10.1051/0004-6361:20053832.
- ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode 1953QB901.W495......
- ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3 ed.), Birkhäuser, ISBN 3540296921, http://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41. The radius (R*) is given by:
- ^ Zorec, J. et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", Astronomy and Astrophysics 501 (1): 297–320, Bibcode 2009A&A...501..297Z, doi:10.1051/0004-6361/200811147
- ^ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1): 359–365, Bibcode 2002ApJ...573..359A, doi:10.1086/340590
- ^ "SIMBAD Astronomical Database". Results for Rigel. http://simbad.u-strasbg.fr/Simbad. Retrieved 2008-04-10.
- ^ Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society 25: 1319, Bibcode 1993AAS...183.1710G, http://www.astro.utoronto.ca/~garrison/mkstds.html, retrieved 2012-02-04
- ^ Kaler, James. "Rigel". http://www.astro.uiuc.edu/~kaler/sow/rigel.html. Retrieved 2007-02-04.
- ^ Richichi; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 431: 773–777, Bibcode 2005A&A...431..773R, doi:10.1051/0004-6361:20042039
- ^ a b c d e f Jedicke, Peter; Levy, David H. (1992). "Regal Rigel". The New Cosmos. Waukesha: Kalmbach Books. pp. 48–53.
- ^ a b c d e Burnham, Robert, Jr. (1978). Burnham's Celestial Handbook. New York: Dover Publications. p. 1300.
- ^ "Daijirin" p. 815 ISBN 978-4-385-13902-9
- ^ Hōei Nojiri "Shin seiza jyunrei" p. 19 ISBN 978-4-12-204128-8
- ^ Mudrooroo (1994). Aboriginal mythology : an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day. London: HarperCollins. p. 142. ISBN 978-1-85538-306-7.
- ^ p. 419, Mythology: Myths, Legends and Fantasies, Janet Parker, Alice Mills, Julie Stanton, Durban, Struik Publishers, 2007.
[edit] External links
- Rigel
- Image of Rigel from APOD
