Barnard's Star

Barnard's Star /ˈbɑːrnərd/ is a very-low-mass red dwarf about 6 light-years away from Earth in the constellation of Ophiuchus. It is the fourth nearest known individual star to the Sun (after the three components of the Alpha Centauri system) and the closest star in the Northern Celestial Hemisphere.[16] Despite its proximity, the star has a dim apparent 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 the American astronomer E. E. Barnard.[17] He was not the first to observe the star (it appeared on Harvard University plates in 1888 and 1890), but in 1916 he measured its proper motion as 10.3 arcseconds per year relative to the Sun, the highest known for any star.[18]

Barnard's Star is among the most studied red dwarfs because of its proximity and favorable location for observation near the celestial equator.[9] 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 an ancient star, it still experiences star flare events, one being observed in 1998.

From the early 1960s to the early 1970s, Peter van de Kamp argued that there were one or more gas giants in orbit around it. 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 is believed to have 3.2 M (Earth masses) and orbit at 0.4 au.[19]

Barnard's Star

The location of Barnard's Star, c. 2006 (south is up)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ophiuchus
Pronunciation /ˈbɑːrnərd/
Right ascension  17h 57m 48.49803s[1]
Declination +04° 41′ 36.2072″[1]
Apparent magnitude (V) 9.511[2]
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
Radial velocity (Rv)−110.6 ± 0.2[5] km/s
Proper motion (μ) RA: −802.803[6] mas/yr
Dec.: 10362.542[6] mas/yr
Parallax (π)547.4506 ± 0.2899[6] mas
Distance5.958 ± 0.003 ly
(1.8266 ± 0.0010 pc)
Absolute magnitude (MV)13.21[2]
Mass0.144[7] M
Radius0.196 ± 0.008[8] R
Luminosity (bolometric)0.0035[9] L
Luminosity (visual, LV)0.0004[9] L
Temperature3,134 ± 102[9] K
Metallicity10–32% Sun[10]
Rotation130.4 d[11]
Age≈ 10[12] Gyr
Other designations
"Barnard's Runaway Star", "Greyhound of the Skies",[13] BD+04°3561a, GCTP 4098.00, Gl 140-024, Gliese 699, HIP 87937, LFT 1385, LHS 57, LTT 15309, Munich 15040, Proxima Ophiuchi,[14] V2500 Ophiuchi, Velox Barnardi,[15] Vyssotsky 799
Database references


In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[20] to catalogue and standardize proper names for stars. The WGSN approved the name Barnard's Star for this star on 1 February 2017 and it is now included in the List of IAU-approved Star Names.[21]


Barnard's Star, showing position every 5 years in the period 1985–2005

Barnard's Star is a red dwarf of the dim spectral type M4, and it is too faint to see without a telescope. Its apparent magnitude is 9.5.

At 7–12 billion years of age, Barnard's Star is considerably older than the Sun, which is 4.5 billion years old, and it might be among the oldest stars in the Milky Way galaxy.[12] Barnard's Star has lost a great deal of rotational energy, and the periodic slight changes in its brightness indicate that it rotates once in 130 days[11] (the Sun rotates in 25). Given its age, Barnard's Star was long assumed to be quiescent in terms of stellar activity. In 1998, astronomers observed an intense stellar flare, showing that Barnard's Star is a flare star.[22] Barnard's Star has the variable star designation V2500 Ophiuchi. In 2003, Barnard's Star presented the first detectable change in the radial velocity of a star caused by its motion. Further variability in the radial velocity of Barnard's Star was attributed to its stellar activity.[23]

Distances to the nearest stars from 20,000 years ago until 80,000 years in the future

The proper motion of Barnard's Star corresponds to a relative lateral speed of 90 km/s. The 10.3 seconds of arc it travels annually amount to a quarter of a degree in a human lifetime, roughly half the angular diameter of the full Moon.[17]

The radial velocity of Barnard's Star towards the Sun is measured from its blueshift to be −110 km/s. Combined with its proper motion, this gives a space velocity (actual velocity relative to the Sun) of −142.6 ± 0.2 km/s. Barnard's Star will make its closest approach to the Sun around 11,800 AD, when it will approach to within about 3.75 light-years.[7]

Proxima Centauri is the closest star to the Sun at a position currently 4.24 light-years distant from it. However, despite Barnard's Star's even closer pass to the Sun in 11,800 AD, it will still not then be the nearest star, since by that time Proxima Centauri will have moved to a yet-nearer proximity to the Sun.[24] At the time of the star's closest pass by the Sun, Barnard's Star will still be too dim to be seen with the naked eye, since its apparent magnitude will only have increased by one magnitude to about 8.5 by then, still being 2.5 magnitudes short of visibility to the naked eye.

Barnard's Star has a mass of about 0.14 solar masses (M),[7] and a radius 15% to 20% of that of the Sun.[9][25] Thus, although Barnard's Star has roughly 150 times the mass of Jupiter (MJ), its radius is only 1.5 to 2.0 times larger, due to its much higher density. Its effective temperature is 3,100 kelvin, and it has a visual luminosity of 0.0004 solar luminosities.[9] Barnard's Star is so faint that if it were at the same distance from Earth as the Sun is, it would appear only 100 times brighter than a full moon, comparable to the brightness of the Sun at 80 astronomical units.[26]

Barnard's Star has 10–32% of the solar metallicity.[10] Metallicity is the proportion of stellar mass made up of elements heavier than helium and helps classify stars relative to the galactic population. Barnard's Star seems to be typical of the old, red dwarf population II stars, yet these are also generally metal-poor halo stars. While sub-solar, Barnard's Star's metallicity is higher than that of a halo star and is in keeping with the low end of the metal-rich disk star range; this, plus its high space motion, have led to the designation "intermediate population II star", between a halo and disk star.[10][23]

Planetary system

The Barnard's Star planetary system
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b 3.23±0.44 M 0.404±0.018 232.80+0.38

In November 2018 an international team of astronomers announced the detection of a candidate super-Earth orbiting in relatively close proximity to Barnard's Star. The large team was led by Ignasi Ribas of Spain and their work included two decades of observation, with their observations giving strong evidence that the planet exists.[19][27]

Dubbed Barnard's Star b, the planet was found near the stellar system's snow line, which is an ideal spot for the icy accretion of proto-planetary material. It orbits at 0.4 AU every 233 days and has a proposed mass of 3.2 M. The planet is most likely frigid, with an estimated surface temperature of about −170 °C (−275 °F), and lies outside Barnard Star's presumed habitable zone. However, more work is needed on the planet's atmospherics to better understand surface conditions. Direct imaging of the planet and its tell-tale light signature are possible in the decade after its discovery. Further faint and unaccounted for perturbations in the system suggest there may be a second planetary companion even further out.[28]

Previous planetary claims

Artist’s impression of the surface of a super-Earth orbiting Barnard’s Star
Artist's impression of the surface of a super-Earth orbiting Barnard's Star.[29]

For a decade from 1963 to about 1973, a substantial number of astronomers accepted a claim by Peter van de Kamp that he had detected, by using astrometry, a perturbation in the proper motion of Barnard's Star consistent with its having one or more planets comparable in mass with Jupiter. Van de Kamp had been observing the star from 1938, attempting, with colleagues at the Sproul Observatory at Swarthmore College, to find minuscule variations of one micrometre in its position on photographic plates consistent with orbital perturbations that would indicate a planetary companion; this involved as many as ten people averaging their results in looking at plates, to avoid systemic individual errors.[30] Van de Kamp's initial suggestion was a planet having about 1.6 MJ at a distance of 4.4 AU in a slightly eccentric orbit,[31] and these measurements were apparently refined in a 1969 paper.[32] Later that year, Van de Kamp suggested that there were two planets of 1.1 and 0.8 MJ.[33]

Artist's conception of a planet in orbit around a red dwarf

Other astronomers subsequently repeated Van de Kamp's measurements, and two papers in 1973 undermined the claim of a planet or planets. George Gatewood and Heinrich Eichhorn, at a different observatory and using newer plate measuring techniques, failed to verify the planetary companion.[34] Another paper published by John L. Hershey four months earlier, also using the Swarthmore observatory, found that changes in the astrometric field of various stars correlated to the timing of adjustments and modifications that had been carried out on the refractor telescope's objective lens;[35] the claimed planet was attributed to an artifact of maintenance and upgrade work. The affair has been discussed as part of a broader scientific review.[36]

Van de Kamp never acknowledged any error and published a further claim of two planets' existence as late as 1982;[37] he died in 1995. Wulff Heintz, Van de Kamp's successor at Swarthmore and an expert on double stars, questioned his findings and began publishing criticisms from 1976 onwards. The two men were reported to have become estranged because of this.[38]

Refining planetary boundaries

For the more than four decades between van de Kamp's rejected claim and the eventual announcement of a planet candidate, Barnard's Star was carefully studied and the mass and orbital boundaries for possible planets were slowly tightened. M dwarfs such as Barnard's Star are more easily studied than larger stars in this regard because their lower masses render perturbations more obvious.[39]

Stars closest to the Sun, including Barnard's Star (25 April 2014)[40]

Null results for planetary companions continued throughout the 1980s and 1990s, including interferometric work with the Hubble Space Telescope in 1999.[41] Gatewood was able to show in 1995 that planets with 10 MJ were impossible around Barnard's Star,[36] in a paper which helped refine the negative certainty regarding planetary objects in general.[42] In 1999, the Hubble work further excluded planetary companions of 0.8 MJ with an orbital period of less than 1,000 days (Jupiter's orbital period is 4,332 days),[41] while Kuerster determined in 2003 that within the habitable zone around Barnard's Star, planets are not possible with an "M sin i" value[43] greater than 7.5 times the mass of the Earth (M), or with a mass greater than 3.1 times the mass of Neptune (much lower than van de Kamp's smallest suggested value).[23]

In 2013, a research paper was published that further refined planet mass boundaries for the star. Using radial velocity measurements, taken over a period of 25 years, from the Lick and Keck Observatories and applying Monte Carlo analysis for both circular and eccentric orbits, upper masses for planets out to 1,000-day orbits were determined. Planets above two Earth masses in orbits of less than 10 days were excluded, and planets of more than ten Earth masses out to a two-year orbit were also confidently ruled out. It was also discovered that the habitable zone of the star seemed to be devoid of roughly Earth-mass planets or larger, save for face-on orbits.[44][45]

Even though this research greatly restricted the possible properties of planets around Barnard's Star, it did not rule them out completely as terrestrial planets were always going to be difficult to detect. NASA's Space Interferometry Mission, which was to begin searching for extrasolar Earth-like planets, was reported to have chosen Barnard's Star as an early search target.[26] This mission was shut down in 2010.[46] ESA's similar Darwin interferometry mission had the same goal, but was stripped of funding in 2007.[47]

The analysis of radial velocities that eventually led to discovery of the candidate super-Earth orbiting Barnard's Star was also used to set more precise upper mass limits for possible planets, up to and within the habitable zone: a maximum of 0.7 M up to the inner edge and 1.2 M on the outer edge of the optimistic habitable zone, corresponding to orbital periods of up to 10 and 40 days respectively. Therefore, it appears that Barnard's Star indeed does not host Earth-mass planets, or larger, in hot and temperate orbits, unlike other M-dwarf stars that commonly have these type of planets in close-in orbits.[19]

Proposed exploration

Project Daedalus

Barnard's Star was studied as part of Project Daedalus. Undertaken between 1973 and 1978, the study suggested that rapid, unmanned travel to another star system was possible with existing or near-future technology.[48] Barnard's Star was chosen as a target partly because it was believed to have planets.[49]

The theoretical model suggested that a nuclear pulse rocket employing nuclear fusion (specifically, electron bombardment of deuterium and helium-3) and accelerating for four years could achieve a velocity of 12% of the speed of light. The star could then be reached in 50 years, within a human lifetime.[49] Along with detailed investigation of the star and any companions, the interstellar medium would be examined and baseline astrometric readings performed.[48]

The initial Project Daedalus model sparked further theoretical research. In 1980, Robert Freitas suggested a more ambitious plan: a self-replicating spacecraft intended to search for and make contact with extraterrestrial life.[50] Built and launched in Jupiter's orbit, it would reach Barnard's Star in 47 years under parameters similar to those of the original Project Daedalus. Once at the star, it would begin automated self-replication, constructing a factory, initially to manufacture exploratory probes and eventually to create a copy of the original spacecraft after 1,000 years.[50]

1998 flare

In 1998 a stellar flare on Barnard's Star was detected based on changes in the spectral emissions on 17 July during an unrelated search for variations in the proper motion. Four years passed before the flare was fully analyzed, at which point it was suggested that the flare's temperature was 8000 K, more than twice the normal temperature of the star.[51] Given the essentially random nature of flares, Diane Paulson, one of the authors of that study, noted that "the star would be fantastic for amateurs to observe".[22]

Artist's conception of a red dwarf

The flare was surprising because intense stellar activity is not expected in stars of such age. Flares are not completely understood, but are believed to be caused by strong magnetic fields, which suppress plasma convection and lead to sudden outbursts: strong magnetic fields occur in rapidly rotating stars, while old stars tend to rotate slowly. For Barnard's Star to undergo an event of such magnitude is thus presumed to be a rarity.[51] Research on the star's periodicity, or changes in stellar activity over a given timescale, also suggest it ought to be quiescent; 1998 research showed weak evidence for periodic variation in the star's brightness, noting only one possible starspot over 130 days.[11]

Stellar activity of this sort has created interest in using Barnard's Star as a proxy to understand similar stars. It is hoped that photometric studies of its X-ray and UV emissions will shed light on the large population of old M dwarfs in the galaxy. Such research has astrobiological implications: given that the habitable zones of M dwarfs are close to the star, any planets would be strongly influenced by solar flares, winds, and plasma ejection events.[12]


Barnard's Star shares much the same neighborhood as the Sun. The neighbors of Barnard's Star are generally of red dwarf size, the smallest and most common star type. Its closest neighbor is currently the red dwarf Ross 154, at 1.66 parsecs' (5.41 light-years) distance. The Sun and Alpha Centauri are, respectively, the next closest systems.[26] From Barnard's Star, the Sun would appear on the diametrically opposite side of the sky at coordinates RA= 5h 57m 48.5s, Dec=−04° 41′ 36″, in the eastern part of the constellation Monoceros. The absolute magnitude of the Sun is 4.83, and at a distance of 1.834 parsecs, it would be a first-magnitude star, as Pollux is from the Earth.[52]

See also

Notes and references

  1. ^ a b Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  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. (1997). "M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale". The Astronomical Journal. 113: 806. arXiv:astro-ph/9611222. Bibcode:1997AJ....113..806G. doi:10.1086/118302.
  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. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog: II/246. Originally Published In: 2003yCat.2246....0C. 2246: 0. Bibcode:2003yCat.2246....0C.
  5. ^ Bobylev, Vadim V. (March 2010). "Searching for Stars Closely Encountering with the Solar System". Astronomy Letters. 36 (3): 220–226. arXiv:1003.2160. Bibcode:2010AstL...36..220B. doi:10.1134/S1063773710030060.
  6. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
  7. ^ a b c Bobylev, V. V. (March 2010), "Searching for stars closely encountering with the solar system", Astronomy Letters, 36 (3): 220–226, arXiv:1003.2160, Bibcode:2010AstL...36..220B, doi:10.1134/S1063773710030060
  8. ^ Demory, B.-O.; et al. (October 2009), "Mass-radius relation of low and very low-mass stars revisited with the VLTI", Astronomy and Astrophysics, 505 (1): 205–215, arXiv:0906.0602, Bibcode:2009A&A...505..205D, doi:10.1051/0004-6361/200911976
  9. ^ a b c d e f Dawson, P. C.; De Robertis, M. M. (2004). "Barnard's Star and the M Dwarf Temperature Scale". The Astronomical Journal. 127 (5): 2909. Bibcode:2004AJ....127.2909D. doi:10.1086/383289.
  10. ^ a b c Gizis, John E. (February 1997). "M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale". The Astronomical Journal. 113 (2): 820. arXiv:astro-ph/9611222. Bibcode:1997AJ....113..806G. doi:10.1086/118302.
  11. ^ a b c Benedict, G. Fritz; McArthur, Barbara; Nelan, E.; Story, D.; Whipple, A. L.; Shelus, P. J.; Jefferys, W. H.; Hemenway, P. D.; Franz, Otto G.; Wasserman, L. H.; Duncombe, R. L.; Van Altena, W.; Fredrick, L. W. (1998). "Photometry of Proxima Centauri and Barnard's star using Hubble Space Telescope fine guidance senso 3". The Astronomical Journal. 116 (1): 429. arXiv:astro-ph/9806276. Bibcode:1998AJ....116..429B. doi:10.1086/300420.
  12. ^ a b c Riedel, A. R.; Guinan, E. F.; DeWarf, L. E.; Engle, S. G.; McCook, G. P. (May 2005). "Barnard's Star as a Proxy for Old Disk dM Stars: Magnetic Activity, Light Variations, XUV Irradiances, and Planetary Habitable Zones". Bulletin of the American Astronomical Society. 37: 442. Bibcode:2005AAS...206.0904R.
  13. ^ "Barnard's Star and its Perturbations". Spaceflight. 11–12: 170. 1969.
  14. ^ Perepelkin, E. (April 1927). "Einweißer Stern mit bedeutender absoluter Größe". Astronomische Nachrichten (in German). 230 (4): 77. Bibcode:1927AN....230...77P. doi:10.1002/asna.19272300406.
  15. ^ Rukl, Antonin (1999). "Constellation Guidebook". Sterling Publishing: 158. ISBN 978-0-8069-3979-7.
  16. ^ "Archived copy". Archived from the original on 26 June 2013. Retrieved 5 May 2013.CS1 maint: Archived copy as title (link)
  17. ^ a b Kaler, James B. (November 2005). "Barnard's Star (V2500 Ophiuchi)". Stars. James B. Kaler. Archived from the original on 5 September 2006. Retrieved 12 July 2018.
  18. ^ Barnard, E. E. (1916). "A small star with large proper motion". The Astronomical Journal. 29 (695): 181. Bibcode:1916AJ.....29..181B. doi:10.1086/104156.
  19. ^ a b c Ribas, I.; Tuomi, M.; Reiners, A.; Butler, R. P.; Morales, J. C.; Perger, M.; Dreizler, S.; Rodríguez-López, C.; González Hernández, J. I. (14 November 2018). "A candidate super-Earth planet orbiting near the snow line of Barnard's star". Nature. 563 (7731): 365–368. arXiv:1811.05955. doi:10.1038/s41586-018-0677-y. ISSN 0028-0836.
  20. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  21. ^ "Naming Stars". Retrieved 16 December 2017.
  22. ^ a b Croswell, Ken (November 2005). "A Flare for Barnard's Star". Astronomy Magazine. Kalmbach Publishing Co. Retrieved 10 August 2006.
  23. ^ a b c Kürster, M.; Endl, M.; Rouesnel, F.; Els, S.; Kaufer, A.; Brillant, S.; Hatzes, A. P.; Saar, S. H.; Cochran, W. D. (2003). "The low-level radial velocity variability in Barnard's Star". Astronomy and Astrophysics. 403 (6): 1077. arXiv:astro-ph/0303528. Bibcode:2003A&A...403.1077K. doi:10.1051/0004-6361:20030396.
  24. ^ Matthews, R. A. J.; Weissman, P. R.; Preston, R. A.; Jones, D. L.; Lestrade, J.-F.; Latham, D. W.; Stefanik, R. P.; Paredes, J. M. (1994). "The Close Approach of Stars in the Solar Neighborhood". Quarterly Journal of the Royal Astronomical Society. 35: 1–9. Bibcode:1994QJRAS..35....1M.
  25. ^ Ochsenbein, F. (March 1982). "A list of stars with large expected angular diameters". Astronomy and Astrophysics Supplement Series. 47: 523–531. Bibcode:1982A&AS...47..523O.
  26. ^ a b c "Barnard's Star". Sol Station. Archived from the original on 20 August 2006. Retrieved 10 August 2006.
  27. ^ "Super-Earth Orbiting Barnard's Star". European Southern Observatory. 14 November 2018. Retrieved 14 November 2018.
  28. ^ Billings, Lee (14 November 2018). "A Frozen Super-Earth May Orbit Barnard's Star". Scientific American. Retrieved 19 November 2018.
  29. ^ "Super-Earth Orbiting Barnard's Star – Red Dots campaign uncovers compelling evidence of exoplanet around closest single star to Sun". Retrieved 15 November 2018.
  30. ^ "The Barnard's Star Blunder". Astrobiology Magazine. July 2005. Retrieved 26 January 2014.
  31. ^ Van de Kamp, Peter. (1963). "Astrometric study of Barnard's star from plates taken with the 24-inch Sproul refractor". The Astronomical Journal. 68 (7): 515. Bibcode:1963AJ.....68..515V. doi:10.1086/109001. Archived
  32. ^ Van de Kamp, Peter. (1969). "Parallax, proper motion acceleration, and orbital motion of Barnard's Star". The Astronomical Journal. 74 (2): 238. Bibcode:1969AJ.....74..238V. doi:10.1086/110799.
  33. ^ Van de Kamp, Peter. (1969). "Alternate dynamical analysis of Barnard's star". The Astronomical Journal. 74 (8): 757. Bibcode:1969AJ.....74..757V. doi:10.1086/110852.
  34. ^ Gatewood, George & Eichhorn, H. (1973). "An unsuccessful search for a planetary companion of Barnard's star (BD +4 3561)". The Astronomical Journal. 78 (10): 769. Bibcode:1973AJ.....78..769G. doi:10.1086/111480.
  35. ^ John L. Hershey (1973). "Astrometric analysis of the field of AC +65 6955 from plates taken with the Sproul 24-inch refractor". The Astronomical Journal. 78 (6): 421. Bibcode:1973AJ.....78..421H. doi:10.1086/111436.
  36. ^ a b Bell, George H. (April 2001). "The Search for the Extrasolar Planets: A Brief History of the Search, the Findings and the Future Implications, Section 2". Arizona State University. Archived from the original on 13 August 2006. Retrieved 10 August 2006.CS1 maint: BOT: original-url status unknown (link) Full description of the Van de Kamp planet controversy.
  37. ^ Van de Kamp, Peter. (1982). "The planetary system of Barnard's star". Vistas in Astronomy. 26 (2): 141. Bibcode:1982VA.....26..141V. doi:10.1016/0083-6656(82)90004-6.
  38. ^ Kent, Bill (2001). "Barnard's Wobble" (PDF). Bulletin. Swarthmore College. Archived from the original (PDF) on 2 June 2010. Retrieved 2 June 2010.
  39. ^ Endl, Michael; Cochran, William D.; Tull, Robert G.; MacQueen, Phillip J. (2003). "A Dedicated M Dwarf Planet Search Using the Hobby-Eberly Telescope". The Astronomical Journal. 126 (12): 3099–107. arXiv:astro-ph/0308477. Bibcode:2003AJ....126.3099E. doi:10.1086/379137.
  40. ^ Clavin, Whitney; Harrington, J.D. (25 April 2014). "NASA's Spitzer and WISE Telescopes Find Close, Cold Neighbor of Sun". NASA. Archived from the original on 26 April 2014. Retrieved 25 April 2014.
  41. ^ a b Benedict, G. Fritz; McArthur, Barbara; Chappell, D. W.; Nelan, E.; Jefferys, W. H.; Van Altena, W.; Lee, J.; Cornell, D.; Shelus, P. J.; Hemenway, P. D.; Franz, Otto G.; Wasserman, L. H.; Duncombe, R. L.; Story, D.; Whipple, A. L.; Fredrick, L. W. (1999). "Interferometric Astrometry of Proxima Centauri and Barnard's Star Using HUBBLE SPACE TELESCOPE Fine Guidance Sensor 3: Detection Limits for Substellar Companions". The Astronomical Journal. 118 (2): 1086–1100. arXiv:astro-ph/9905318. Bibcode:1999AJ....118.1086B. doi:10.1086/300975.
  42. ^ George D. Gatewood (1995). "A study of the astrometric motion of Barnard's star". Journal Astrophysics and Space Science. 223 (1): 91–98. Bibcode:1995Ap&SS.223...91G. doi:10.1007/BF00989158.
  43. ^ "M sin i" means the mass of the planet times the sine of the angle of inclination of its orbit, and hence provides the minimum mass for the planet.
  44. ^ Gilster, Paul (16 August 2012). "Barnard's Star: No Sign of Planets". Centauri Dreams. Retrieved 11 April 2018.
  45. ^ Choi, Jieun; McCarthy, Chris; Marcy, Geoffrey W; Howard, Andrew W; Fischer, Debra A; Johnson, John A; Isaacson, Howard; Wright, Jason T (2012). "Precise Doppler Monitoring of Barnard's Star". The Astrophysical Journal. 764 (2): 131. arXiv:1208.2273. Bibcode:2013ApJ...764..131C. doi:10.1088/0004-637X/764/2/131.
  46. ^ Marr, James (8 November 2010). "Updates from the Project Manager". NASA. Archived from the original on 2 March 2011. Retrieved 26 January 2014.
  47. ^ "Darwin factsheet: Finding Earth-like planets". European Space Agency. 23 October 2009. Archived from the original on 13 May 2008. Retrieved 12 September 2011.
  48. ^ a b Bond, A. & Martin, A.R. (1976). "Project Daedalus – The mission profile". Journal of the British Interplanetary Society. 29 (2): 101. Bibcode:1976JBIS...29..101B. Archived from the original on 20 October 2007. Retrieved 15 August 2006.
  49. ^ a b Darling, David (July 2005). "Daedalus, Project". The Encyclopedia of Astrobiology, Astronomy, and Spaceflight. Archived from the original on 31 August 2006. Retrieved 10 August 2006.
  50. ^ a b Freitas, Robert A., Jr. (July 1980). "A Self-Reproducing Interstellar Probe". Journal of the British Interplanetary Society. 33: 251–264. Bibcode:1980JBIS...33..251F. Retrieved 1 October 2008.
  51. ^ a b Paulson, Diane B.; Allred, Joel C.; Anderson, Ryan B.; Hawley, Suzanne L.; Cochran, William D.; Yelda, Sylvana (2006). "Optical Spectroscopy of a Flare on Barnard's Star". Publications of the Astronomical Society of the Pacific. 118 (1): 227. arXiv:astro-ph/0511281. Bibcode:2006PASP..118..227P. doi:10.1086/499497.
  52. ^ The Sun's apparent magnitude from Barnard's Star, assuming negligible extinction: .


External links

Coordinates: Sky map 17h 57m 48.5s, +04° 41′ 36″

Barnard's Star b

Barnard's Star b (also designated GJ 699 b) is a candidate super-Earth-like exoplanet and ice planet that orbits Barnard's Star in the constellation of Ophiuchus. The exoplanet's discovery by an international team of astronomers, including the European Southern Observatory, and Carnegie Institution for Science was officially announced, through the Nature journal on 14 November, 2018. It is the first confirmed planet orbiting Barnard's Star, which is six light years away from Earth.

Flare star

A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars' atmospheres. The brightness increase is across the spectrum, from X rays to radio waves. The first known flare stars (V1396 Cygni and AT Microscopii) were discovered in 1924. However, the best-known flare star is UV Ceti, discovered in 1948. Today similar flare stars are classified as UV Ceti type variable stars (using the abbreviation UV) in variable star catalogs such as the General Catalogue of Variable Stars.

Most flare stars are dim red dwarfs, although recent research indicates that less massive brown dwarfs might also be capable of flaring. The more massive RS Canum Venaticorum variables (RS CVn) are also known to flare, but it is understood that these flares are induced by a companion star in a binary system which causes the magnetic field to become tangled. Additionally, nine stars similar to the Sun had also been seen to undergo flare events prior

to the flood of superflare data from the Kepler observatory.

It has been proposed that the mechanism for this is similar to that of the RS CVn variables in that the flares are being induced by a companion, namely an unseen Jupiter-like planet in a close orbit.

George David Gatewood

George David Gatewood (born 1940) also known as George G. Gatewood, is an American astronomer and presently is professor emeritus at the University of Pittsburgh and at the Allegheny Observatory. He specializes in astronomy, astronomical instrumentation, statistical methods, stellar astrophysics, astrometric properties of nearby stars and the observational discovery and the study of planetary systems. He came to popular attention with his 1996 announcement of the discovery of a nearby multi-planet star system. This discovery has yet to be confirmed and is regarded with skepticism today.

Innes' star

Innes' star (Gliese 422) is an M3.5-type red dwarf, located in constellation Carina. It has around 35% of the mass of the Sun, yet only 1.1% of its luminosity, and an estimated surface temperature of 3,323 K.It is known for the fact that it had once been considered one of the nearest stars to Earth, due to erroneously measured parallax. The estimated distance was less than 10 light-years in the following studies:

In List of stars nearer than 5 parsecs by Ejnar Hertzsprung (1922) its parallax is 0.339 arcsec (distance is 2.95 pc or 9.62 ly), and it is the 4th closest star system after Alpha Centauri ABC, Barnard's Star and Sirius AB;

In A study of the near-by stars by Willem Jacob Luyten and Harlow Shapley (1930) its parallax is 0.337 arcsec (distance is 2.97 pc or 9.68 ly), and it is the 4th closest star system after Alpha Centauri ABC, Barnard's Star and 22 H Camelopardalis (Sirius is further);

In List of stars nearer than five parsecs by Peter van de Kamp (1930) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 7th closest star system after Alpha Centauri ABC, Barnard's Star, Wolf 359, Lalande 21185, Sirius AB and BD-12 4523;

In Stars within ten parsecs of the Sun by Louise Freeland Jenkins (1937) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 6th closest star system after Alpha Centauri, Barnard's Star, Wolf 359, Lalande 21185 and Sirius.Its actual distance is 12.7 pc or 41.3 light-years, based on parallax by van Leeuwen (2007): 0.07813±0.00054 arcsec.Innes' star was discovered in 1920 by Robert T. A. Innes in Union Observatory, Union of South Africa, who had discerned its large proper motion and a parallax of 0.337 arcsec. The discovery was published in Circular of the Union Observatory No. 49, hence its discovery name is UO 49, or In UOC 49. However, UO designations should be used with caution since they are often not unique for each star: the number in the name is the number of Circular, so all stars published in one Circular have identical names. So, all other newfound stars, published in the 49th Circular, may be named UO 49 too.

In 2014, a Mega-Earth or a mini-Neptune GJ 422 b of approximately 10-Earth-masses was discovered in the system of this star, orbiting the star every 26 days and lying at a distance of around 0.11 astronomical units (AU)—11% of the distance between our Earth and Sun—in the stellar system's habitable zone, which for this star has been calculated to lie between 0.11 and 0.21 AU.This star is one of a few stars named after people — named after a scientist, whereas the majority of proper names of stars have ancient origins or medieval, in the main Arabic, ones. Certain stars, found to be nearby due to their large proper motion, also fall into this class and are named after their discoverers: Barnard's Star; Kapteyn's Star; Luyten's Star; van Maanen's Star: van Biesbroeck's Star; and Teegarden's Star. Innes is also known as the discoverer of Proxima Centauri.

Life on Another Planet

Life On Another Planet, also known as Signal from Space, is a science fiction graphic novel by Will Eisner dealing with the social and political consequences of a first contact with an extraterrestrial civilization. It was first serialized in The Spirit and later collected into a single volume.

Luhman 16

Luhman 16 (WISE 1049−5319, WISE J104915.57−531906.1) is a binary brown-dwarf system in the southern constellation Vela at a distance of approximately 6.5 light-years (2.0 parsecs) from the Sun. These are the closest-known brown dwarfs and the closest system found since the measurement of the proper motion of Barnard's Star in 1916, and the third-closest-known system to the Sun (after the Alpha Centauri system and Barnard's Star). The primary is of spectral type L7.5 and the secondary of type T0.5 ± 1 (and is hence near the L–T transition). The masses of Luhman 16 A and B are 33.5 and 28.6 Jupiter masses, respectively, and their ages are estimated to be 600–800 million years. Luhman 16 A and B orbit each other at a distance of about 3.5 astronomical units with an orbital period of approximately 27 years.

Marooned on Eden

Marooned on Eden (1993), is a science fiction novel by Robert L. Forward, collaborating with his wife, Martha Dodson Forward.It is part of the Rocheworld series, about an expedition to explore planets found in orbit around Barnard's Star. It was written before Ocean Under the Ice, but is after it in the continuity. This is the fourth book in the continuity. It is written from the perspective of crewmember Reiki LeRoux and revolves around the crew struggling to survive on the habitable moon Zuni after a crash landing maroons them there.

The crew nevertheless do their best to continue the mission without technology, learning to communicate with the moon's inhabitants and eventually building a home and raising families. It is the only book in the series written from a first person perspective.

Ocean Under the Ice

Ocean Under the Ice is a science fiction novel by Robert L. Forward, collaborating with his wife, Martha Dodson Forward. It is part of the Rocheworld series, about an expedition to explore planets found in orbit around Barnard's Star. It was written after Marooned on Eden, but is before it in the continuity. This is the third book in the continuity. It follows the crew of humans and Flouwen as they explore Zulu, a moon of the gas planet Gargantua, and encounter 2 sentient species, the icerugs and the coelasharks.

Peter van de Kamp

Piet van de Kamp (December 26, 1901 in Kampen – May 18, 1995 in Amsterdam), known as Peter van de Kamp in the United States, was a Dutch astronomer who lived in the United States most of his life. He was professor of astronomy at Swarthmore College and director of the college's Sproul Observatory from 1937 until 1972. He specialized in astrometry, studying parallax and proper motions of stars. He came to public attention in the 1960s when he announced that Barnard's star had a planetary system based on observed "wobbles" in of its motion, but this is now known to be false.

On November 14, 2018 the Red Dots project announced that Barnard's star hosts an exoplanet at least 3.2 times as massive as Earth.

Project Daedalus

Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible unmanned interstellar spacecraft. Intended mainly as a scientific probe, the design criteria specified that the spacecraft had to use existing or near-future technology and had to be able to reach its destination within a human lifetime. Alan Bond led a team of scientists and engineers who proposed using a fusion rocket to reach Barnard's Star 5.9 light years away. The trip was estimated to take 50 years, but the design was required to be flexible enough that it could be sent to any other target star.

Rescued from Paradise

Rescued from Paradise is a science fiction novel by Robert L. Forward, collaborating with his daughter Julie Forward Fuller. It is part of the Rocheworld series, about an

expedition to explore planets found in orbit around Barnard's Star. This is the fifth and final book in the continuity. Some material from previous novels was rewritten and included as part of this story.

In this novel, after settling down on the habitable moon Zuni (Now known as Eden), the crew struggle to survive various disasters and to communicate with a mysterious Civilization under the ocean.

Return to Rocheworld

Return to Rocheworld is a 1993 science fiction novel by Robert L. Forward and Julie Forward Fuller. It is the sequel to Forward's Rocheworld (also known as The Flight of the Dragonfly), a novel about the first manned interstellar mission to a unique double planet orbiting Barnard's Star. It features a return journey to that planet by the crew of the lightsail powered Starship Prometheus.

Several new characters are introduced, including Reiki LeRoux , who makes only a brief appearance in this novel but is the main protagonist in a sequel novel, Marooned on Eden.

The Flouwen are also featured more extensively, and Flouwen culture is explored. A new species, the Gummies, is also introduced, living on the Roche lobe of the strange double planet.

The story picks up where the Rocheworld left off, but before the final chapter set years later. Major General Virginia "Jinjur" Jones leads a return journey to Rocheworld, where they set up a communication station for the flouwen to use. Having discovered that the Roche lobe of the planet is subject to periodic flooding, the explorers return there along with several Flouwen, (including one youngling who wants to be like the humans) to find that Roche also harbors not only life, but intelligence as well. They find a species which they come to call the Gummies, after their resemblance to the texture of gummi candy. These beings are related to the Flouwen of the water-covered Eau lobe, but have evolved in a completely different direction. Built to survive harsh conditions, extremes of temperature, long droughts, and competing for scarce food supplies, these elephant-sized multi-tentacled creatures are far more physical and aggressive than their aquatic ancestors. However, by the end of the novel, they have begun to develop the beginnings of a crude stone age technology. The Flouwen figure out how to operate the Dragonfly II Spaceplane and take several gummies back to Eau, to the objection of the humans. Finally, the humans and 3 Flouwen "littles" (Little White, Little Red, and Little Purple) lift off to explore the rest of the Barnard System.


Rocheworld (first published in serial form in 1982; first book publication, under the title The Flight of the Dragonfly, 1984) is a science fiction novel by Robert Forward which depicts a realistic interstellar mission using a laser driven light sail propulsion system to send the spaceship and a crew of 20 on a journey of 5.9 light-years (ca. 34 trillion miles; ca. 56 trillion km) to the double planet that orbits Barnard's Star, which they call Rocheworld, where they make startling discoveries stranger than anything ever encountered before.

It had four sequels, written in collaboration with Julie Forward Fuller and Margaret Dodson Forward, which detail the exploration of the other worlds in the Barnard System: Return to Rocheworld, Marooned on Eden, Ocean Under the Ice, and Rescued from Paradise.

The Alien Encounters

The Alien Encounters is a 1979 science fiction film written and directed by James T. Flocker. It is an American B movie which follows the story of an investigator who is sent to locate an alien probe which has landed on Earth. Aliens from Barnard's Star have created a machine known as a betatron which has remarkable rejuvenating effects.

Described by leading science fiction author David Wingrove in his Science Fiction Source Book as a "Deathly dull B-movie UFO story with dire effects and no real encounters at all...Endless desert scenes and interminable talk-overs disguise crank concerns of writer/director James T. Flocker", the film received generally poor reviews.

Filmed in and around the Calico Mountains including Mule Canyon Road and scenes on the lake bed, off Ghost Town Road and Interstate 15, 7 miles north of Barstow, California.

The Big Jump

The Big Jump is a science fiction novel by American writer Leigh Brackett, centered on the first manned expedition to Barnard's Star.

The Black Corridor

The Black Corridor is a science fiction novel by Michael Moorcock. It was published in 1969, first by Ace Books in the US, as part of their Ace Science Fiction Specials series, and later by Mayflower Books in the UK.

It is essentially a novel about the decay of society and the deep personal and social isolation this has caused, and tells of a man fleeing through interstellar space from Earth, where civilisation is collapsing into anarchy and wars. The author uses techniques ranging from straight narrative to entries in the spaceship's log, dream sequences and sixties-style computer printouts.

The Legion of Space

The Legion of Space is a science fiction novel by the American writer Jack Williamson. It was originally serialized in Astounding Stories in 1934, then published in book form (with some revisions) by Fantasy Press in 1947 in an edition of 2,970 copies. A magazine-sized reprint was issued by Galaxy in 1950, with a standard paperback following from Pyramid Books in 1967. The first British edition was published by Sphere Books in 1977. The Legion of Space has been translated into German, French and Italian. It has also appeared in the omnibus Three from the Legion, which compiles the novel and all but one of its sequels.

WISE 0855−0714

WISE 0855−0714 (full designation WISE J085510.83−071442.5) is a sub-brown dwarf 2.23±0.04 parsecs (7.27±0.13 light-years) from Earth, the discovery of which was announced in April 2014 by Kevin Luhman using data from the Wide-field Infrared Survey Explorer (WISE). As of 2014, WISE 0855−0714 has the third-highest proper motion (8118±8 mas/yr) after Barnard's Star (10300 mas/yr) and Kapteyn's Star (8600 mas/yr) and the fourth-largest parallax (449±8 mas) of any known star or brown dwarf, meaning it is the fourth-closest extrasolar system to the Sun. It is also the coldest object of its type found in interstellar space, having a temperature in the range 225 to 260 K (−48 to −13 °C; −55 to 8 °F).

Wulff-Dieter Heintz

Wulff-Dieter Heintz (3 June 1930 – 10 June 2006) was a German astronomer who worked the latter part of his career in the United States. He was Professor Emeritus of Astronomy at Swarthmore College. He was an active astronomer who specialised in the characterisation of binary stars using astrometry.

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.