50-558: Kapteyn may refer to: Jacobus Kapteyn - Astronomer Parallactic instrument of Kapteyn - the instrument used by Kapteyn to analyze photographic plates Jacobus Kapteyn Telescope - telescope named after Jacobus Kapteyn Kapteyn's Star - star named after Jacobus Kapteyn Kapteyn (crater) - Lunar crater named after Jacobus Kapteyn Kapteyn Astronomical Institute - Dutch Astronomical Institute named after Jacobus Kapteyn Paul Joan George Kapteyn - Dutch Judge Topics referred to by
100-426: 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 8,000 K, more than twice the normal temperature of the star. Given the essentially random nature of flares, Diane Paulson, one of
150-466: A candidate super-Earth planetary companion was reported to orbit Barnard's Star. It was believed to have a minimum mass of 3.2 M E and orbit at 0.4 AU . However, work presented in July 2021 refuted the existence of this planet. 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 ,
200-487: A close-orbiting sub-Earth discovered in 2024, with additional candidates suspected. Previously, it was subject to multiple claims of planets that were disproven. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) 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
250-461: A distance of 1.66 parsecs (5.41 light-years). The Sun (5.98 light-years) and Alpha Centauri (6.47 light-years) are, respectively, the next closest systems. From Barnard's Star, the Sun would appear on the diametrically opposite side of the sky at coordinates RA= 5 57 48.5 , Dec=−04° 41′ 36″, in the westernmost part of the constellation Monoceros . The absolute magnitude of
300-498: A great deal of rotational energy; the periodic slight changes in its brightness indicate that it rotates once in 130 days (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 . Barnard's Star has the variable star designation V2500 Ophiuchi. In 2003, Barnard's Star presented
350-484: A more ambitious plan: a self-replicating spacecraft intended to search for and make contact with extraterrestrial life . 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
400-542: 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. Along with detailed investigation of the star and any companions, the interstellar medium would be examined and baseline astrometric readings performed. The initial Project Daedalus model sparked further theoretical research. In 1980, Robert Freitas suggested
450-489: A paper which helped refine the negative certainty regarding planetary objects in general. In 1999, the Hubble work further excluded planetary companions of 0.8 M J with an orbital period of less than 1,000 days (Jupiter's orbital period is 4,332 days), while Kuerster determined in 2003 that within the habitable zone around Barnard's Star, planets are not possible with an " M sin i " value greater than 7.5 times
500-487: 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
550-610: A photographic survey of southern hemisphere stars at the Royal Observatory at the Cape of Good Hope . The results of this collaboration was the publication of Cape Photographic Durchmusterung , a catalog listing positions and magnitudes for 454,875 stars in the Southern Hemisphere . In 1897, as part of the above work, he discovered Kapteyn's Star . It had the highest proper motion of any star known until
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#1732775664157600-456: A plan for a major study of the distribution of stars in the Galaxy, using counts of stars in different directions. The plan involved measuring the apparent magnitude , spectral type , radial velocity , and proper motion of stars in 206 zones. This enormous project was the first coordinated statistical analysis in astronomy and involved the cooperation of over forty different observatories. He
650-558: A planetary companion; this involved as many as ten people averaging their results in looking at plates, to avoid systemic individual errors. Van de Kamp's initial suggestion was a planet having about 1.6 M J at a distance of 4.4 AU in a slightly eccentric orbit, and these measurements were apparently refined in a 1969 paper. Later that year, Van de Kamp suggested that there were two planets of 1.1 and 0.8 M J . Other astronomers subsequently repeated Van de Kamp's measurements, and two papers in 1973 undermined
700-484: 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 . Its stellar mass is about 16% of the Sun's, and it has 19% of the Sun's diameter. Despite its proximity,
750-454: 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. 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
800-461: Is among the most studied red dwarfs because of its proximity and favorable location for observation near the celestial equator . 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. Barnard's Star hosts at least one planet,
850-434: Is designated Barnard's Star b (or Barnard b), a re-use of the designation originally used for the refuted super-Earth candidate. 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,
900-471: Is different from Wikidata All article disambiguation pages All disambiguation pages Jacobus Kapteyn Jacobus Cornelius Kapteyn (19 January 1851 – 18 June 1922) was a Dutch astronomer . He carried out extensive studies of the Milky Way . He found that the apparent movement of stars was not randomly distributed but had two preferential directions: the two star streams. This discovery
950-414: Is enough to cause loss of 87 Earth atmospheres per billion years through thermal processes and ≈3 Earth atmospheres per billion years through ion loss processes on Barnard's Star b. 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
1000-591: 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 planet located therein would be strongly affected by solar flares, stellar winds , and plasma ejection events. In 2019, two additional ultraviolet stellar flares were detected, each with far-ultraviolet energy of 3×10 joules, together with one X-ray stellar flare with energy 1.6×10 joules. The flare rate observed to date
1050-609: Is named after Kapteyn. A street in the city of Groningen is also named after Kapteyn: the J.C. Kapteynlaan. And the Isaac Newton Group of Telescopes on La Palma in the Canary Islands named the Jacobus Kapteyn Telescope (JKT) after him. His daughter Henrietta (1881-1956) married astronomer Ejnar Hertzsprung . Awards Named after him Barnard%27s Star Barnard's Star is
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#17327756641571100-455: Is now included in the List of IAU-approved Star Names. Barnard's Star is a red dwarf of the dim spectral type M4 and 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. Barnard's Star has lost
1150-426: Is only roughly 2 times larger, due to its much higher density. Its effective temperature is about 3,220 kelvin , and it has a luminosity of only 0.0034 solar luminosities . 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 . Barnard's Star has 10–32% of
1200-403: 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 CE, 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. At the time of the star's closest pass by the Sun, Barnard's Star will still be too dim to be seen with
1250-417: Is thus presumed to be a rarity. 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. Stellar activity of this sort has created interest in using Barnard's Star as a proxy to understand similar stars. It
1300-616: The Leiden Observatory , before becoming the first Professor of Astronomy and Theoretical Mechanics at the University of Groningen , where he remained until his retirement in 1921. In 1888 he became a member of the Royal Netherlands Academy of Arts and Sciences . Between 1896 and 1900, lacking an observatory, he volunteered to measure photographic plates taken by David Gill , who was conducting
1350-496: The Very Large Telescope , the existence of an exoplanet with a minimum mass of 0.37 ± 0.05 M 🜨 and orbital period of 3.15 days was confirmed. This constituted the first convincing evidence for a planet orbiting Barnard's Star. Additionally, three other candidate low-mass planets were proposed in this study. All of these planets orbit closer to the star than the habitable zone . The confirmed planet
1400-518: 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. Barnard's Star was studied as part of Project Daedalus . Undertaken between 1973 and 1978, the study suggested that rapid, uncrewed travel to another star system was possible with existing or near-future technology. Barnard's Star was chosen as a target partly because it was believed to have planets. The theoretical model suggested that
1450-507: The authors of that study, noted that "the star would be fantastic for amateurs to observe". 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
1500-498: 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. 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
1550-399: The detection by radial velocity of a candidate super-Earth orbiting in relatively close proximity to Barnard's Star. Led by Ignasi Ribas of Spain their work, conducted over two decades of observation, provided strong evidence of the planet's existence. However, the existence of the planet was refuted in 2021, when the radial velocity signal was found to originate from long-term activity on
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1600-552: The discovery of Barnard's Star in 1916. In 1904, studying the proper motions of stars, Kapteyn reported that these were not random, as it was believed in that time; stars could be divided into two streams, moving in nearly opposite directions. It was later realized that Kapteyn's data had been the first evidence of the rotation of the Milky Way Galaxy, which ultimately led to the finding of galactic rotation by Bertil Lindblad and Jan Oort . In 1906, Kapteyn launched
1650-414: 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. The proper motion of Barnard's Star corresponds to a relative lateral speed of 90 km/s. The 10.3 arcseconds it travels in a year amount to a quarter of a degree in a human lifetime, roughly half the angular diameter of
1700-485: The full Moon. The radial velocity of Barnard's Star is −110 km/s , as measured from the blueshift due to its motion toward the Sun. Combined with its proper motion and distance, this gives a "space velocity" (actual speed 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 CE, when it will approach to within about 3.75 light-years. Proxima Centauri
1750-437: 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. However, some recently published scientific papers have given much higher estimates for the metallicity of the star, very close to the Sun's level, between 75 and 125% of the solar metallicity. In August 2024, by using data from ESPRESSO spectrograph of
1800-578: 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. Null results for planetary companions continued throughout the 1980s and 1990s, including interferometric work with the Hubble Space Telescope in 1999. Gatewood was able to show in 1995 that planets with 10 M J were impossible around Barnard's Star, in
1850-682: The mass of the Earth ( M E ), or with a mass greater than 3.1 times the mass of Neptune (much lower than van de Kamp's smallest suggested value). 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
1900-400: 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 0.16 solar masses ( M ☉ ), and a radius about 0.2 times that of the Sun. Thus, although Barnard's Star has roughly 150 times the mass of Jupiter ( M J ), its radius
1950-403: The planet and its tell-tale light signature would have been possible in the decade after its discovery. Further faint and unaccounted-for perturbations in the system suggested there may be a second planetary companion even farther out. 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
2000-627: The refractor telescope's objective lens; 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. Van de Kamp never acknowledged any error and published a further claim of two planets' existence as late as 1982; 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. In November 2018, an international team of astronomers announced
2050-411: The same term [REDACTED] This disambiguation page lists articles associated with the title Kapteyn . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Kapteyn&oldid=1207084292 " Category : Disambiguation pages Hidden categories: Short description
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2100-413: The solar metallicity . 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
2150-471: 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 , 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. Barnard's Star
2200-590: The star itself, related to its rotation. Further studies in the following years confirmed this result. Dubbed Barnard's Star b, the planet was thought to be near the stellar system's snow line , which is an ideal spot for the icy accretion of proto-planetary material. It was thought to orbit at 0.4 AU every 233 days and had a proposed minimum mass of 3.2 M E . The planet would have most likely been frigid, with an estimated surface temperature of about −170 °C (−274 °F), and lie outside Barnard Star's presumed habitable zone . Direct imaging of
2250-535: 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 E up to the inner edge and 1.2 M E 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 types of planets in close-in orbits. In 1998
2300-486: Was awarded the James Craig Watson Medal in 1913. Kapteyn later retired in 1921 at the age of seventy, but on the request of his former student and director of Leiden Observatory Willem de Sitter , Kapteyn went back to Leiden to assist in upgrading the observatory to contemporary astronomical standards. His life's work, First attempt at a theory of the arrangement and motion of the sidereal system ,
2350-490: Was later reinterpreted as evidence for galactic rotation . Kapteyn also suggested that these stellar velocities could be used to find the amount of non-luminous matter in the galaxy. Kapteyn was born in Barneveld to Gerrit J. and Elisabeth C. (née Koomans) Kapteyn, and went to the University of Utrecht to study mathematics and physics in 1868. In 1875, after having finished his thesis , he worked for three years at
2400-521: Was only after Kapteyn's death, in Amsterdam , that Robert Trumpler determined that the amount of interstellar reddening was actually much greater than had been assumed. This discovery increased the estimate of the galaxy's size to 100,000 light years, with the Sun replaced to a distance of 30,000 light years from the Galactic Center . The astronomy institute of the University of Groningen
2450-517: Was published in 1922, and described a lens-shaped island universe of which the density decreased away from the center, now known as the Kapteyn Universe . In his model the Galaxy was thought to be 40,000 light years in size, the Sun being relatively close (2,000 light years) to its center. The model was valid at high galactic latitudes but failed in the galactic plane because of the lack of knowledge of interstellar absorption. It
2500-404: Was to begin searching for extrasolar Earth-like planets, was reported to have chosen Barnard's Star as an early search target, however the mission was shut down in 2010. ESA 's similar Darwin interferometry mission had the same goal, but was stripped of funding in 2007. The analysis of radial velocities that eventually led to the announcement of a candidate super-Earth orbiting Barnard's Star
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