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Barnard's Star

Barnard's Star

The location of Barnard's Star, c. 2006 (south is up)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ophiuchus
Right ascension 17h 57m 48.49847s[1]
Declination +04° 41′ 36.1139″[1]
Apparent magnitude (V) 9.511[2]
Characteristics
Spectral type M4.0V[3]
Apparent magnitude (U) 12.497[2]
Apparent magnitude (B) 11.240[2]
Apparent magnitude (R) 8.298[2]
Apparent magnitude (I) 6.741[2]
Apparent magnitude (J) 5.24[4]
Apparent magnitude (H) 4.83[4]
Apparent magnitude (K) 4.524[4]
U−B color index 1.257[2]
B−V color index 1.713[2]
V−R color index 1.213[2]
R−I color index 1.557[2]
Variable type BY Draconis[5]
Astrometry
Radial velocity (Rv)−110.47±0.13[1] km/s
Proper motion (μ) RA: −801.551 mas/yr[1]
Dec.: 10362.394 mas/yr[1]
Parallax (π)546.9759 ± 0.0401 mas[1]
Distance5.9629 ± 0.0004 ly
(1.8282 ± 0.0001 pc)
Absolute magnitude (MV)13.21[2]
Details
Mass0.1610+0.0036
−0.0035[6] M☉
Radius0.187±0.001[6] R☉
Luminosity (bolometric)0.00340±0.00006[6] L☉
Luminosity (visual, LV)0.0004[7] L☉
Temperature3,223±17[6] K
Rotation145±15 d[8]
Age≈ 10[9] Gyr
Other designations
Proxima Ophiuchi[10], "Barnard's Runaway Star"[11], "Greyhound of the Skies"[12], V2500 Ophiuchi, BD+04°3561a, GJ 699, HIP 87937, LFT 1385, LHS 57, LTT 15309, 2MASS J17574849+0441405, GCTP 4098.00, Gl 140-024, Karmn J17578+046, Munich 15040,[13] Vyssotsky 799, Latin: Velox Barnardi[14]
Database references
SIMBADdata
ARICNSdata
Barnard's Star is located in the constellation Ophiuchus.
Barnard's Star is located in the constellation Ophiuchus.
Barnard's Star
Location of Barnard's Star in the constellation Ophiuchus

Barnard's Star is a small red dwarf star in the constellation of Ophiuchus. At a distance of 5.96 light-years (1.83 pc) from Earth, it is the fourth-nearest-known individual star to the Sun after the three components of the Alpha Centauri system, and is the closest star in the northern celestial hemisphere.[15] Its stellar mass is about 16% of the Sun's, and it has 19% of the Sun's diameter. Despite its proximity, the star has a dim apparent visual magnitude of +9.5 and is invisible to the unaided eye; it is much brighter in the infrared than in visible light.

The star is named after Edward Emerson Barnard,[16] an American astronomer who in 1916 measured its proper motion as 10.3 arcseconds per year relative to the Sun, the highest known for any star. The star had previously appeared on Harvard University photographic plates in 1888 and 1890.[17]

Barnard's Star is among the most studied red dwarfs because of its proximity and favorable location for observation near the celestial equator.[7] Historically, research on Barnard's Star has focused on measuring its stellar characteristics, its astrometry, and also refining the limits of possible extrasolar planets. Although Barnard's Star is ancient, it still experiences stellar flare events, one being observed in 1998.[18]

Barnard's Star has been subject to multiple claims of planets that were later disproven. From the early 1960s to the early 1970s, Peter van de Kamp argued that planets orbited Barnard's Star. His specific claims of large gas giants were refuted in the mid-1970s after much debate. In November 2018, a candidate super-Earth planetary companion known as Barnard's Star b was reported to orbit Barnard's Star. It was believed to have a minimum mass of 3.2 ME and orbit at 0.4 AU.[19] However, work presented in July 2021 refuted the existence of this planet.[20]

  1. ^ a b c d e Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b c d e f g h i j Koen, C.; Kilkenny, D.; Van Wyk, F.; Marang, F. (2010). "UBV(RI)C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society. 403 (4): 1949. Bibcode:2010MNRAS.403.1949K. doi:10.1111/j.1365-2966.2009.16182.x.
  3. ^ Gizis, John E. (February 1997). "M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale". The Astronomical Journal. 113 (2): 806–822. arXiv:astro-ph/9611222. Bibcode:1997AJ....113..806G. doi:10.1086/118302. S2CID 16863021.
  4. ^ a b c Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (June 2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. 2246. Bibcode:2003yCat.2246....0C.
  5. ^ Samus, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2009) [First published 2009]. "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+, 2007–2017)". VizieR On-line Data Catalog: B/gcvs. 1: B/gcvs. Bibcode:2009yCat....102025S.
  6. ^ a b c d Cite error: The named reference Pineda2021 was invoked but never defined (see the help page).
  7. ^ a b Dawson, P. C.; De Robertis, M. M. (May 2004). "Barnard's Star and the M Dwarf Temperature Scale". The Astronomical Journal. 127 (5): 2909–2914. Bibcode:2004AJ....127.2909D. doi:10.1086/383289.
  8. ^ Cite error: The named reference Terrien2022 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Riedel2005 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference an230_77 was invoked but never defined (see the help page).
  11. ^ Lippincott, Sarah Lee (1960). "A Model of our Stellar Neighborhood". Astronomical Society of the Pacific Leaflets. 8 (377): 207. Bibcode:1960ASPL....8..207L.
  12. ^ Cite error: The named reference bis11_12_170 was invoked but never defined (see the help page).
  13. ^ Seeliger, Hugo; Bauschinger, Julius (1890). "Erstes Müchner Sternverzeichniss enthaltend die mittleren Örter von 33082 Sternen". Neue Annalen der Koeniglichen Sternwarte in Bogenhausen bei Muenchen. 1: 1. Bibcode:1890AnBog...1....1S.
  14. ^ Cite error: The named reference rukl1999 was invoked but never defined (see the help page).
  15. ^ "Astronomy Survey Fall 2010". Archived from the original on 26 June 2013. Retrieved 5 May 2013.
  16. ^ Cite error: The named reference Kaler was invoked but never defined (see the help page).
  17. ^ Barnard, E. E. (September 1916). "A small star with large proper motion". The Astronomical Journal. 29 (695): 181–183. Bibcode:1916AJ.....29..181B. doi:10.1086/104156.
  18. ^ Cite error: The named reference PaulsonFlare was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference Ribas was invoked but never defined (see the help page).
  20. ^ Cite error: The named reference Lubin2021 was invoked but never defined (see the help page).

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