Rigel

From Wikipedia, the free encyclopedia
Jump to: navigation, search
For other uses, see Rigel (disambiguation).
Rigel
Orion constellation map.svg

Rigel in the constellation Orion
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
A
Right ascension 05h 14m 32.27210s[1]
Declination −08° 12′ 05.8981″[1]
Apparent magnitude (V) 0.13[2] (0.05 - 0.18[3])
B
Right ascension 05h 14m 32.049s[4]
Declination −08° 12′ 14.78″[4]
Apparent magnitude (V) 6.67[5]
Characteristics
A
Evolutionary stage Blue supergiant
Spectral type B8 Ia[6]
U−B color index −0.66[7]
B−V color index −0.03[7]
Variable type Alpha Cygni[8]
B
Evolutionary stage Spectroscopic binary
Spectral type B9V + B9V[9]
U−B color index −0.66[7]
B−V color index −0.03[7]
Variable type Alpha Cygni[8]
Astrometry
Radial velocity (Rv) 17.8±0.4[10] km/s
Proper motion (μ) RA: +1.31[1] mas/yr
Dec.: +0.50[1] mas/yr
Parallax (π) 3.78 ± 0.34[1] mas
Distance 860 ± 80 ly
(260 ± 20 pc)
Absolute magnitude (MV) -7.84[11]
Orbit[5]
Primary Ba
Companion Bb
Period (P) 9.860 days
Eccentricity (e) 0.1
Semi-amplitude (K1)
(primary)
25.0 km/s
Semi-amplitude (K2)
(secondary)
32.6 km/s
Details
A
Mass 23[12] M
Radius 78.9±7.4[13] R
Luminosity (bolometric) 1.20+0.25
−0.21
×105[13] L
Surface gravity (log g) 1.75±0.10[12] cgs
Temperature 12100±150[12] K
Metallicity [Fe/H] −0.06±0.10[6] dex
Rotational velocity (v sin i) 25±3[12] km/s
Age 8±1[6] Myr
Ba
Mass 3.84[9] M
Bb
Mass 2.94[9] M
Other designations
Rigel, Algebar, Elgebar, β Ori, 19 Ori, HD 34085, HR 1713, HIP 24436, SAO 131907[14]
Database references
SIMBAD data

Rigel, also designated Beta Orionis (β Orionis, abbreviated Beta Ori, β Ori), is generally the seventh-brightest star in the night sky and the brightest star in the constellation of Orion—though there are times where it is outshone in the constellation by the variable Betelgeuse. With a visual magnitude of 0.13, it is a remote and luminous star some 863 light-years distant from Earth.

The star as seen from Earth is actually a triple or quadruple star system, with the primary star (Rigel A) a blue-white supergiant that is estimated to be anywhere from 120,000 to 279,000 times as luminous as the Sun, depending on method used to calculate its properties. It has exhausted its core hydrogen and swollen out to between 79 and 115 times the Sun's radius. It pulsates quasi-periodically and is classified as an Alpha Cygni variable. A companion, Rigel B, is 500 times fainter than the supergiant Rigel A and visible only with a telescope. Rigel B is itself a spectroscopic binary system, consisting of two main sequence blue-white stars of spectral type B9V that are estimated to be respectively 3.9 and 2.9 times as massive as the Sun. Rigel B also appears to have a very close visual companion Rigel C of almost identical appearance.

Nomenclature[edit]

Beta Orionis is the star's Bayer designation. The traditional name Rigel is first recorded in the Alfonsine Tables of 1252. It is derived from the Arabic name Rijl Jauzah al Yusrā, "the left leg (foot) of Jauzah" (i.e. rijl meaning "leg, foot"),[15] which can be traced to the 10th century.[16] "Jauzah" was a proper name of the Orion figure, an alternative Arabic name was رجل الجبار riǧl al-ǧabbār, "the foot of the great one", which is the source of the rarely used variant names Algebar or Elgebar. The Alphonsine Tables saw its name split into "Rigel" and "Algebar", with the note, "et dicitur Algebar. Nominatur etiam Rigel."[17] Alternate spellings from the 17th century include Regel by Giovanni Battista Riccioli, Riglon by Wilhelm Schickard, and Rigel Algeuze or Algibbar by Edmund Chilmead.[15]

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[18] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[19] included a table of the first two batches of names approved by the WGSN; which included Rigel for this star. It is now so entered in the IAU Catalog of Star Names.[20]

Rigel is presumably the star known as "Aurvandil's toe" in Norse mythology.[21]

In Chinese astronomy, Rigel is the seventh star of the "Three Stars" asterism, 参宿七 (Shēnxiù Qī). In Japan, the Minamoto or Genji clan had chosen Rigel and its white color as its symbol, calling the star Genji-boshi (源氏星), while the Taira or Heike clan adopted Betelgeuse and its red color. The two powerful families fought a legendary war in Japanese history, the stars seen as facing each other off and only kept apart by the Belt.[22][23][24] Rigel was also known as Gin-waki, (銀脇), "the Silver (Star) beside (Mitsu-boshi)."

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.[25] The indigenous Boorong people of northwestern Victoria named Rigel as Collowgullouric Warepil.[26] The Wardaman people of northern Australia know Rigel as the Red Kangaroo Leader Unumburrgu and chief conductor of ceremonies in a songline when Orion is high in the sky. The river Eridanus marks a line of stars in the sky leading to it, and the other stars of Orion are his ceremonial tools and entourage. Betelgeuse is Ya-jungin "Owl Eyes Flicking", watching the ceremonies.[27]

The Māori people named Rigel as Puanga and was said to be a daughter of Rehua (Antares), the chief of all stars.[28] Its heliacal rising also presaged the appearance of Matariki (the Pleiades) in the dawn sky which marked the Māori New Year in late May or early June. The Moriori people of the Chatham Islands, as well as some Maori groups in New Zealand marked the start of their New Year with Rigel rather than the Pleiades.[29] Puaka was a local variant used in the South Island.[30]

The Lacandon people knew it as tunsel "little woodpecker".[31]

Visibility[edit]

The apparent visual magnitude of Rigel is 0.13, making it on average the seventh-brightest star in the celestial sphere excluding the Sun—just fainter than Capella. It is an irregular pulsating variable with a visual range of magnitude 0.05–0.18. 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.[32] Rigel is the third most inherently luminous first magnitude star after Deneb and Betelgeuse. Rigel has a color index (B–V) of −0.03, meaning it appears white or slightly blue-white.[33]

Culminating at midnight on 12 December, and at 9 pm on 24 January, Rigel is most visible in winter evenings in the northern hemisphere and summer in the southern.[34] In the southern hemisphere, Rigel is the first bright star of Orion visible as the constellation rises.[35] 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 (the exception, areas within 8° of the North Pole).

Parallax[edit]

The new Hipparcos reduction of Rigel's parallax gives a distance of 863 light-years (265 parsecs), with a margin of error of about 9%.[1] Earlier spectroscopic estimates placed its distance between 360 and 500 parsecs (1,200 and 1,600 light-years).[36][37]

System[edit]

Rigel has been known as a visual double star since at least 1822, when it was measured by Friedrich Georg Wilhelm von Struve.[38] The companion is not particularly faint at magnitude 6.7, and with a separation of 9.5 arcsec both components are resolvable in most amateur astronomer's telescopes.[38] However, the large difference in brightness makes it a challenging target for telescope apertures smaller than 15.0 cm (5.9 in).[39] At Rigel's estimated distance, Rigel B's projected separation from its primary is over 2200 AU. Since its discovery, there has been no sign of orbital movement, although both stars share similar common proper motion.[38][40] The pair would have an minimum orbital period of around 18,000 years.[9]

Since the 19th century, Rigel B has been reported to be resolved into a close binary of two equal components, with the measured separation varying from less than 0.1" to nearly 0.2". Speckle interferometry showed in 2009 two almost identical components separated by 0.124".[41] Both stars have apparent visual magnitudes of 7.6 with a likely orbital period of 63 years.[9]

Rigel B is itself a spectroscopic binary system, consisting of two main sequence stars that orbit each other every 9.86 days. The stars both belong to the spectral class B9. These two stars do not appear to make up the visual binary components B and C, so the system might be a triple star, although the true arrangement of them is unclear.[42]

A 15.4 magnitude star at 44.6 arcsec in north position angle of 1° is catalogued as component D in the system although it is unclear whether it is physically related or a coincidental alignment.[38]

Properties[edit]

Rigel's place at top center on the Hertzsprung-Russell diagram

Moravveji and colleagues calculate a luminosity for Rigel A of 120,000 times that of the Sun.[13] Its surface temperature is around 12,100 K. The interferometer-measured angular diameter of this star, after correction for limb darkening, is 2.75±0.01 mas.[43] At its estimated distance, this yields a size of about 79 times the radius of the Sun.[13] Norbert Przybilla and colleagues used atmospheric modelling in 2006 to come up with a distance of 360 ± 40 parsecs (1,170 ± 130 light-years). They calculated it to be around 218,000 times as luminous as the Sun, and have around 21±3 solar masses and 109±12 times its radius.[6] The CMFGEN code is an atmosphere code used to determine the properties of massive stars from analysing their spectrum and atmosphere. Analysis of Rigel using this method yields a luminosity 279,000 times that of the Sun, a radius 115 times that of the Sun and stellar wind velocity of 671,080 miles per hour.[44]

Rigel A is a blue supergiant that has exhausted burning the hydrogen fuel in its core and left the main sequence, expanding and brightening as it progresses across the Hertzsprung–Russell diagram. Przybilla estimated that it has lost around 3 solar masses since beginning life as a star of 24 ± 3 solar masses 7 to 9 million years ago.[6] It will become a red supergiant and eventually end its stellar life by exploding as a type II supernova, in the process flinging out material that will serve to seed future generations of stars.[8] It is one of the closest known potential supernova progenitors to Earth.[13]

Rigel's variability is complex and is 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 with periods ranging from about 1.2 to 74 days.[13] It is notable among blue supergiant stars in the sense that while its pulsations are powered by the nuclear reactions in a hydrogen-burning shell that is at least partially non-convective, the star also burns helium in its core.[8] Rigel was identified as belonging to the Alpha Cygni variables in 1998 by Christoffel Waelkens and colleagues.[45]

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).[40] 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 although it is considerably closer than most of the members. Betelgeuse and Saiph lie at a similar distance to Rigel, although Betelgeuse is a runaway star with a complex history and is likely to have originally formed in the main body of the association.[46] It has been listed as a member of the poorly-defined Taurus-Orion R1 Association[47]

The companions Rigel Ba, Bb, and C all appear to be similar B class main sequence stars of 3 - 4 M, but their properties are not accurately known.[9]

Space photometry[edit]

Rigel and reflection nebula IC 2118 in Eridanus. Rigel B is not visible in the glare of the main star.

Rigel was observed with the Canadian MOST satellite for nearly 28 days in 2009. The light variations in this supergiant star were at the milli magnitude level. The gradual changes in the flux highlights the presence of long-period pulsation modes in the star.[13]

Spectroscopy[edit]

The general spectral type of Rigel as B8 is well-established and it has been used as a defining point of the spectral classification sequence for supergiants. However the details of the spectrum vary considerably owing to periodic atmospheric eruptions. The spectral lines show emission, absorption, line doubling, P Cygni profiles, and inverse P Cygni profiles, with no obvious periodicity.[48] This has resulted in classification as B8 Iab, B8 Iae, or blendings by different authors.[11][46]

See also[edit]

References[edit]

  1. ^ a b c d e f van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D. 
  3. ^ Guinan, E. F.; Eaton, J. A.; Wasatonic, R.; Stewart, H.; Engle, S. G.; McCook, G. P. (2010). "Times-Series Photometry & Spectroscopy of the Bright Blue Supergiant Rigel: Probing the Atmosphere and Interior of a SN II Progenitor". Proceedings of the International Astronomical Union. 5: 359. Bibcode:2010HiA....15..359G. doi:10.1017/S1743921310009798. 
  4. ^ a b DENIS Consortium (2005). "VizieR Online Data Catalog: The DENIS database (DENIS Consortium, 2005)". VizieR On-line Data Catalog: B/denis. Originally published in: 2005yCat.2263....0T. 1. Bibcode:2005yCat....102002D. 
  5. ^ a b Sanford, Roscoe F. (1942). "The Spectrographic Orbit of the Companion to Rigel". Astrophysical Journal. 95: 421. Bibcode:1942ApJ....95..421S. doi:10.1086/144412. 
  6. ^ a b c d e Przybilla, N.; et al. (January 2006). "Quantitative spectroscopy of BA-type supergiants". Astronomy and Astrophysics. 445 (3): 1099–1126. arXiv:astro-ph/0509669Freely accessible. Bibcode:2006A&A...445.1099P. doi:10.1051/0004-6361:20053832. 
  7. ^ a b c d 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. 
  8. ^ a b c d Moravveji, Ehsan; Moya, Andres; Guinan, Edward F. (April 2012). "Asteroseismology of the nearby SN-II Progenitor: Rigel. Part II. ε-mechanism Triggering Gravity-mode Pulsations?". The Astrophysical Journal. 749 (1): 74–84. arXiv:1202.1836Freely accessible. Bibcode:2012ApJ...749...74M. doi:10.1088/0004-637X/749/1/74. 
  9. ^ a b c d e f Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy & Astrophysics Supplement Series. 124: 75. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181. 
  10. ^ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  11. ^ a b Shultz, M.; Wade, G. A.; Petit, V.; Grunhut, J.; Neiner, C.; Hanes, D.; MiMeS Collaboration (2014). "An observational evaluation of magnetic confinement in the winds of BA supergiants". Monthly Notices of the Royal Astronomical Society. 438 (2): 1114. arXiv:1311.5116Freely accessible. Bibcode:2014MNRAS.438.1114S. doi:10.1093/mnras/stt2260. 
  12. ^ a b c d Przybilla, N. (2010). "Mixing of CNO-cycled matter in massive stars". Astronomy and Astrophysics. 517: A38. arXiv:1005.2278Freely accessible. Bibcode:2010A&A...517A..38P. doi:10.1051/0004-6361/201014164. 
  13. ^ a b c d e f g Moravveji, Ehsan; Guinan, Edward F.; Shultz, Matt; Williamson, Michael H.; Moya, Andres (March 2012). "Asteroseismology of the nearby SN-II Progenitor: Rigel. Part I. The MOST High-precision Photometry and Radial Velocity Monitoring". The Astrophysical Journal. 747 (1): 108–115. arXiv:1201.0843Freely accessible. Bibcode:2012ApJ...747..108M. doi:10.1088/0004-637X/747/2/108. 
  14. ^ "SIMBAD Astronomical Database". Results for Rigel. Retrieved 2008-04-10. 
  15. ^ a b Allen, Richard Hinckley (1963) [1899]. Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. pp. 312–13. ISBN 0-486-21079-0. 
  16. ^ Kunitzsch, Paul (1959). Arabische Sternnamen in Europa. Wiesbaden: Otto Harrassowitz. p. 46. 
  17. ^ Kunitzsch, P. (1986). "The Star Catalogue Commonly Appended to the Alfonsine Tables". Journal for the History of Astronomy. 17: 89. Bibcode:1986JHA....17...89K. 
  18. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016. 
  19. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016. 
  20. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  21. ^ Richard Cleasby, An Icelandic-English Dictionary, Clarendon Press, 1874, s.v. auvandils-tá.
  22. ^ Steve Renshaw & Saori Ihara (October 1999). "Yowatashi Boshi; Stars that Pass in the Night". Griffith Observer. Retrieved 25 June 2012. 
  23. ^ "Daijirin" p. 815 ISBN 978-4-385-13902-9
  24. ^ Hōei Nojiri "Shin seiza jyunrei" p. 19 ISBN 978-4-12-204128-8
  25. ^ 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. 
  26. ^ Hamacher, Duane W.; Frew, David J. (2010). "An Aboriginal Australian Record of the Great Eruption of Eta Carinae". Journal of Astronomical History & Heritage. 13 (3): 220–34. arXiv:1010.4610Freely accessible. Bibcode:2010JAHH...13..220H. 
  27. ^ Harney, Bill Yidumduma; Cairns, Hugh C. (2004) [2003]. Dark Sparklers (Revised ed.). Merimbula, New South Wales: Hugh C. Cairns. pp. 139–40. ISBN 0-9750908-0-1. 
  28. ^ p. 419, Mythology: Myths, Legends and Fantasies, Janet Parker, Alice Mills, Julie Stanton, Durban, Struik Publishers, 2007.
  29. ^ Kelley, David H.; Milone, Eugene F. (2011). Exploring Ancient Skies: A Survey of Ancient and Cultural Astronomy. Springer. p. 341. ISBN 144197623X. 
  30. ^ Best, Elsdon (1922). Astronomical Knowledge of the Maori: Genuine and Empirical. Wellington, New Zealand: Dominion Museum. pp. 39–40. 
  31. ^ Milbrath, Susan (1999). Star Gods of the Maya: Astronomy in Art, Folklore, and Calendars. Austin, Texas: University of Texas Press. p. 39. ISBN 0292752261. 
  32. ^ 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. 
  33. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, 21 December 2004, retrieved 28 June 2014 
  34. ^ Schaaf, Fred (2008). "Appendix C". The Brightest Stars. Hoboken, New Jersey: Wiley. p. 257. ISBN 0-471-70410-5. 
  35. ^ Ellyard, David; Tirion, Wil (2008) [1993]. The Southern Sky Guide (3rd ed.). Port Melbourne, Victoria: Cambridge University Press. pp. 58–59. ISBN 978-0-521-71405-1. 
  36. ^ Humphreys, R. M. (1978). "Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way". Astrophysical Journal. 38: 309. Bibcode:1978ApJS...38..309H. doi:10.1086/190559. 
  37. ^ Hoffleit, Dorrit; Jaschek, Carlos (1991). "The Bright star catalogue". New Haven. Bibcode:1991bsc..book.....H. <
  38. ^ a b c d "Washington Double Star Catalogue". US Naval Observatory. Retrieved 13 March 2016. 
  39. ^ Burnham, Robert, Jr. (1978). Burnham's Celestial Handbook. New York: Dover Publications. p. 1300. 
  40. ^ a b Jedicke, Peter; Levy, David H. (1992). "Regal Rigel". The New Cosmos. Waukesha: Kalmbach Books. pp. 48–53. 
  41. ^ Mason, Brian D.; Hartkopf, William I.; Gies, Douglas R.; Henry, Todd J.; Helsel, John W. (2009). "The High Angular Resolution Multiplicity of Massive Stars". The Astronomical Journal. 137 (2): 3358. arXiv:0811.0492Freely accessible. Bibcode:2009AJ....137.3358M. doi:10.1088/0004-6256/137/2/3358. 
  42. ^ "Spectroscopic Binary Catalogue (SB9)". D.Pourbaix. Retrieved 13 March 2016. 
  43. ^ Aufdenberg, J. P.; et al. (2008). "Limb Darkening: Getting Warmer". The Power of Optical/IR Interferometry. Eso Astrophysics Symposia. 1 (1): 71–82. Bibcode:2008poii.conf...71A. doi:10.1007/978-3-540-74256-2_8. ISBN 978-3-540-74253-1. 
  44. ^ =Chesneau, O.; Kaufer, A.; Stahl, O.; Colvinter, C.; Spang, A.; Dessart, L.; Prinja, R.; Chini, R. (2014). "The variable stellar wind of Rigel probed at high spatial and spectral resolution". Astronomy & Astrophysics. 566: 18. arXiv:1405.0907Freely accessible. Bibcode:2014A&A...566A.125C. doi:10.1051/0004-6361/201322894. A125. 
  45. ^ Waelkens, C.; Aerts, C.; Kestens, E.; Grenon, M.; Eyer, L. (1998). "Study of an unbiased sample of B stars observed with Hipparcos: the discovery of a large amount of new slowly pulsating B star". Astronomy and Astrophysics. 330: 215–21. Bibcode:1998A&A...330..215W. 
  46. ^ a b Bally, J. (2008). "Overview of the Orion Complex". Handbook of Star Forming Regions: 459. arXiv:0812.0046Freely accessible. Bibcode:2008hsf1.book..459B. 
  47. ^ Racine, R. (1968). "Stars in reflection nebulae". Astronomical Journal. 73: 233. Bibcode:1968AJ.....73..233R. doi:10.1086/110624. 
  48. ^ Rother, Sara (2009). "A time series study of Rigel, a B8Ia supergiant". 

External links[edit]

Media related to Rigel at Wikimedia Commons

Coordinates: Sky map 05h 14m 32.272s, −08° 12′ 05.91″