Betelgeuse

This article is about the star. For the 1988 film, see Beetlejuice. For other uses, see Betelgeuse (disambiguation).

Betelgeuse
Map of the constellation Orion
Location of Betelgeuse (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
Pronunciation /ˈbɛtəldʒuːz, ˈbiːt-, -dʒuːs/ BE(E)T-əl-jooz, -⁠jooss[1][2] (see below)
Right ascension 05h 55m 10.30536s[3]
Declination +07° 24′ 25.4304″[3]
Apparent magnitude (V) +0.50[4] (0.0–1.6[5])
Characteristics
Evolutionary stage Red supergiant
Spectral type M1–M2 Ia–ab[6]
Apparent magnitude (J) −3.00[7]
Apparent magnitude (K) −4.05[7]
U−B color index +2.06[4]
B−V color index +1.85[4]
Variable type SRc[8]
Astrometry
Radial velocity (Rv)+21.91[9] km/s
Proper motion (μ) RA: 26.42±0.25[10] mas/yr
Dec.: 9.60±0.12[10] mas/yr
Parallax (π)5.95+0.58
−0.85 mas[11]
Distance408 – 548+90
−49 ly
(125[12] – 168.1+27.5
−14.9[11] pc)
Absolute magnitude (MV)−5.85[13]
Details
Mass14[12] – 19[11] M☉
Radius~640[14]–764+116
−62[11] R☉
Luminosity~65,000[14]–87,100+20,500
−11,200[11] L☉
Surface gravity (log g)−0.5[15] cgs
Temperature3,600±200[11] – 3800[12] K
Metallicity [Fe/H]+0.05[16] dex
Rotation36±8[17] years
Rotational velocity (v sin i)5.47±0.25[17] km/s
Age8.0[18]–14[12] Myr
Other designations
Betelgeuse, α Ori, 58 Ori, HR 2061, BD+7°1055, HD 39801, FK5 224, HIP 27989, SAO 113271, GC 7451, CCDM J05552+0724, AAVSO 0549+07
Database references
SIMBADdata

Betelgeuse is a red supergiant star in the constellation of Orion. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in its constellation. It is a distinctly reddish, semiregular variable star whose apparent magnitude, varying between +0.0 and +1.6, has the widest range displayed by any first-magnitude star. Betelgeuse is the brightest star in the night sky at near-infrared wavelengths. Its Bayer designation is α Orionis, Latinised to Alpha Orionis and abbreviated Alpha Ori or α Ori.[19]

With a radius between 640 and 764 times that of the Sun,[14][11] if it were at the center of our Solar System, its surface would lie beyond the asteroid belt and it would engulf the orbits of Mercury, Venus, Earth, and Mars. Calculations of Betelgeuse's mass range from slightly under ten to a little over twenty times that of the Sun. For various reasons, its distance has been quite difficult to measure; current best estimates are of the order of 400–600 light-years from the Sun – a comparatively wide uncertainty for a relatively nearby star. Its absolute magnitude is about −6. With an age of less than 10 million years, Betelgeuse has evolved rapidly because of its large mass, and is expected to end its evolution with a supernova explosion, most likely within 100,000 years. When Betelgeuse explodes, it will shine as bright as the half-Moon for more than three months; life on Earth will be unharmed. Having been ejected from its birthplace in the Orion OB1 association – which includes the stars in Orion's Belt – this runaway star has been observed to be moving through the interstellar medium at a speed of 30 km/s, creating a bow shock over four light-years wide.

Betelgeuse became the first extrasolar star whose photosphere's angular size was measured in 1920, and subsequent studies have reported an angular diameter (i.e., apparent size) ranging from 0.042 to 0.056 arcseconds; that range of determinations is ascribed to non-sphericity, limb darkening, pulsations and varying appearance at different wavelengths. It is also surrounded by a complex, asymmetric envelope, roughly 250 times the size of the star, caused by mass loss from the star itself. The Earth-observed angular diameter of Betelgeuse is exceeded only by those of R Doradus and the Sun.

Starting in October 2019, Betelgeuse began to dim noticeably, and by mid-February 2020 its brightness had dropped by a factor of approximately 3, from magnitude 0.5 to 1.7. It then returned to a more normal brightness range, reaching a peak of 0.0 visual and 0.1 V-band magnitude in April 2023. Infrared observations found no significant change in luminosity over the last 50 years, suggesting that the dimming was due to a change in extinction around the star rather than a more fundamental change. A study using the Hubble Space Telescope suggests that occluding dust was created by a surface mass ejection; this material was cast millions of miles from the star, and then cooled to form the dust that caused the dimming.

  1. ^ Cite error: The named reference OED was invoked but never defined (see the help page).
  2. ^ "Merriam-Webster Dictionary: Betelgeuse". Retrieved 23 April 2018.
  3. ^ a b Cite error: The named reference hipparcos was invoked but never defined (see the help page).
  4. ^ a b c Nicolet, B. (1978). "Catalogue of Homogeneous Data in the UBV Photoelectric Photometric System". Astronomy & Astrophysics. 34: 1–49. Bibcode:1978A&AS...34....1N.
  5. ^ "Alpha Orionis". Variable Star Index. Retrieved 20 February 2020.
  6. ^ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373. S2CID 123149047.
  7. ^ a b 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. Bibcode:2002yCat.2237....0D.
  8. ^ Samus, N.N.; Durlevich, O.V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-Line Data Catalog: B/gcvs. 1: 1. Bibcode:2009yCat....102025S. Originally published in Bibcode:2009yCat....102025S
  9. ^ Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430: 165–186. arXiv:stro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
  10. ^ a b Cite error: The named reference harper2017 was invoked but never defined (see the help page).
  11. ^ a b c d e f g Cite error: The named reference joyce2020 was invoked but never defined (see the help page).
  12. ^ a b c d Cite error: The named reference colordiagram was invoked but never defined (see the help page).
  13. ^ Lambert, D.L.; Brown, J.A.; Hinkle, K.H.; Johnson, H.R. (September 1984). "Carbon, nitrogen and oxygem abundances in Betelgeuse". Astrophysical Journal. 284: 223–237. Bibcode:1984ApJ...284..223L. doi:10.1086/162401. ISSN 0004-637X.
  14. ^ a b c Mittag, M.; Schröder, K. -P.; Perdelwitz, V.; Jack, D.; Schmitt, J. H. M. M. (1 January 2023), "Chromospheric activity and photospheric variation of α Ori during the great dimming event in 2020", Astronomy and Astrophysics, 669: A9, arXiv:2211.04967, Bibcode:2023A&A...669A...9M, doi:10.1051/0004-6361/202244924, ISSN 0004-6361
  15. ^ Lobel, Alex; Dupree, Andrea K. (2000). "Modeling the variable chromosphere of α Orionis". The Astrophysical Journal. 545 (1): 454–74. Bibcode:2000ApJ...545..454L. doi:10.1086/317784.
  16. ^ Ramírez, Solange V.; Sellgren, K.; Carr, John S.; Balachandran, Suchitra C.; Blum, Robert; Terndrup, Donald M.; Steed, Adam (July 2000). "Stellar Iron Abundances at the Galactic Center". The Astrophysical Journal. 537 (1): 205–20. arXiv:astro-ph/0002062. Bibcode:2000ApJ...537..205R. doi:10.1086/309022. S2CID 14713550.
  17. ^ a b Kervella, Pierre; Decin, Leen; Richards, Anita M.S.; Harper, Graham M.; McDonald, Iain; O'Gorman, Eamon; Montargès, Miguel; Homan, Ward; Ohnaka, Keiichi (2018). "The close circumstellar environment of Betelgeuse. V. Rotation velocity and molecular envelope properties from ALMA". Astronomy and Astrophysics. 609: A67. arXiv:1711.07983. Bibcode:2018A&A...609A..67K. doi:10.1051/0004-6361/201731761. S2CID 54670700.
  18. ^ Dolan, Michelle M.; Mathews, Grant J.; Lam, Doan Duc; Lan, Nguyen Quynh; Herczeg, Gregory J.; Dearborn, David S.P. (2017). "Evolutionary Tracks for Betelgeuse". The Astrophysical Journal. 819 (1): 7. arXiv:1406.3143v2. Bibcode:2016ApJ...819....7D. doi:10.3847/0004-637X/819/1/7. S2CID 37913442.
  19. ^ Ohnaka, K.; Weigelt, G.; Millour, F.; Hofmann, K.-H.; Driebe, T.; Schertl, D.; Chelli, A.; Massi, F.; Petrov, R.; Stee, Ph. (25 April 2011). "Imaging the dynamical atmosphere of the red supergiant Betelgeuse in the CO first overtone lines with VLTI/AMBER". Astronomy & Astrophysics. 529: A163. arXiv:1104.0958. Bibcode:2011A&A...529A.163O. doi:10.1051/0004-6361/201016279. ISSN 0004-6361.