The discrepancy was first noted by amateur astronomer Thomas Barker, squire of Lyndon Hall in Rutland, who prepared a paper and spoke at a meeting of the Royal Society in London in 1760.
Seven ships of the Royal Navy have been called since the 18th century, with the first being the flagship of the First Fleet to Australia in 1788.
The existence of other stars changing in brightness gave credibility to the idea that some may change in colour too; Sir John Herschel noted this in 1839, possibly influenced by witnessing Eta Carinae two years earlier.
It is now known to have a parallax of arcseconds and therefore a distance of . === Discovery of Sirius B === In 1844, the German astronomer Friedrich Wilhelm Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion.
On 31 January 1862, American telescope-maker and astronomer Alvan Graham Clark first observed the faint companion, which is now called Sirius B, or affectionately "the Pup".
The bright stars Aldebaran, Arcturus and Sirius were noted to have moved significantly; Sirius had progressed about 30 arc minutes (about the diameter of the Moon) to the southwest. In 1868, Sirius became the first star to have its velocity measured, the beginning of the study of celestial radial velocities.
Thomas Jefferson Jackson See resurrected discussion on red Sirius with the publication of several papers in 1892, and a final summary in 1926.
Since 1894, some apparent orbital irregularities in the Sirius system have been observed, suggesting a third very small companion star, but this has never been confirmed.
The outer atmosphere of Sirius B is now almost pure hydrogen—the element with the lowest mass—and no other elements are seen in its spectrum. === Apparent third star === Since 1894, irregularities have been observed in the orbits of Sirius A and B with an apparent periodicity of 6–6.4 years.
Effectively, there are almost certainly no additional bodies in the Sirius system larger than a small brown dwarf or large exoplanet. === Star cluster membership === In 1909, Ejnar Hertzsprung was the first to suggest that Sirius was a member of the Ursa Major Moving Group, based on his observations of the system's movements across the sky.
An apparent "third star" observed in the 1920s is now believed to be a background object. In 1915, Walter Sydney Adams, using a 60-inch (1.5 m) reflector at Mount Wilson Observatory, observed the spectrum of Sirius B and determined that it was a faint whitish star.
An apparent "third star" observed in the 1920s is now believed to be a background object. In 1915, Walter Sydney Adams, using a 60-inch (1.5 m) reflector at Mount Wilson Observatory, observed the spectrum of Sirius B and determined that it was a faint whitish star.
Thomas Jefferson Jackson See resurrected discussion on red Sirius with the publication of several papers in 1892, and a final summary in 1926.
Twiss in 1959 at Jodrell Bank using their stellar intensity interferometer.
The Voyager 2 spacecraft, launched in 1977 to study the four giant planets in the Solar System, is expected to pass within of Sirius in approximately 296,000 years. == Stellar system == Sirius is a binary star system consisting of two white stars orbiting each other with a separation of about 20 AU (roughly the distance between the Sun and Uranus) and a period of 50.1 years.
The name was also adopted by Mitsubishi Motors as the Mitsubishi Sirius engine in 1980.
It was the standard white star in ancient China, and multiple records from the 2nd century BCE up to the 7th century CE all describe Sirius as white. In 1985, German astronomers Wolfhard Schlosser and Werner Bergmann published an account of an 8th-century Lombardic manuscript, which contains De cursu stellarum ratio by St.
In 1991, anthropologist Walter van Beek concluded about the Dogon, "Though they do speak about sigu tolo [which is what Griaule claimed the Dogon called Sirius] they disagree completely with each other as to which star is meant; for some it is an invisible star that should rise to announce the sigu [festival], for another it is Venus that, through a different position, appears as sigu tolo.
After a periastron occurred in 1994, the pair moved apart, making them easier to separate with a telescope.
A 1995 study concluded that such a companion likely exists, with a mass of roughly 0.05 solar masses – a small red dwarf or large brown dwarf, with an apparent magnitude of more than 15, and less than 3 arcseconds from Sirius A. More recent (and accurate) astrometric observations by the Hubble Space Telescope ruled out the existence of such a Sirius C entirely.
The 1995 study predicted an astrometric movement of roughly 90 mas (0.09 arcseconds), but Hubble was unable to detect any location anomaly to an accuracy of 5 mas (0.005 arcsec).
The name of the North American satellite radio company CD Radio was changed to Sirius Satellite Radio in November 1999, being named after "the brightest star in the night sky".
Analyses in 2003 and 2005 found Sirius's membership in the group to be questionable: the Ursa Major Group has an estimated age of 500 ± 100 million years, whereas Sirius, with metallicity similar to the Sun's, has an age that is only half this, making it too young to belong to the group.
In 2005, using the Hubble Space Telescope, astronomers determined that Sirius B has nearly the diameter of the Earth, , with a mass 102% of the Sun's. === Colour controversy === Around the year 150 CE, the Greek astronomer of the Roman period, Ptolemy of Alexandria mapped the stars in Books VII and VIII of his Almagest, in which he used Sirius as the location for the globe's central meridian.
Analyses in 2003 and 2005 found Sirius's membership in the group to be questionable: the Ursa Major Group has an estimated age of 500 ± 100 million years, whereas Sirius, with metallicity similar to the Sun's, has an age that is only half this, making it too young to belong to the group.
Observations published in 2008 were unable to detect either a third star or a planet.
The Chandra X-ray Observatory image shows Sirius B outshining its partner as an X-ray source. In 2015, Vigan and colleagues used the VLT Survey Telescope to search for evidence of substellar companions, and were able to rule out the presence of giant planets 11 times more massive than Jupiter at 0.5 AU distance from Sirius A, 6–7 times the mass of Jupiter at 1–2 AU distance, and down to around 4 times the mass of Jupiter at 10 AU distance. === Sirius A === Sirius A has a mass of .
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars.
The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Sirius for the star α Canis Majoris A.
To the naked eye, it often appears to be flashing with red, white, and blue hues when near the horizon. === Distant star cluster === In 2017, a massive star cluster was discovered only 10 arcminutes from Sirius, making the two appear to be visually close to one other when viewed from the point of view of the Earth.
Apoastron occurred in 2019, but from the Earth's vantage point, the greatest observational separation will occur in 2023, with an angular separation of 11.333". At a distance of 2.6 parsecs (8.6 ly), the Sirius system contains two of the eight nearest stars to the Sun, and it is the fifth closest stellar system to the Sun.
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