Sirius appears bright because of its intrinsicluminosity and its proximity to theSolar System. At a distance of 2.64parsecs (8.6 ly), the Sirius system is one of Earth'snearest neighbours. Sirius is gradually moving closer to the Solar System and it is expected to increase in brightness slightly over the next 60,000 years to reach a peak magnitude of −1.68.Coincidentally, at about the same time, Sirius will take its turn as the southern Pole Star, around the year 66,270 AD. In that year, Sirius will come to within 1.6 degrees of the south celestial pole. This is due toaxial precession and proper motion of Sirius itself which moves slowly in the SSW direction, so it will be visible from the southern hemisphere only.[26] After that time, its distance will begin to increase, and it will become fainter, but it will continue to be the brightest star in the Earth's night sky for approximately the next 210,000 years, at which pointVega, anotherA-type star that is intrinsically more luminous than Sirius, becomes the brightest star.[27]
Sirius A is about twice as massive as theSun (M☉) and has anabsolute visual magnitude of +1.43. It is 25 timesas luminous as the Sun,[18] but has a significantly lower luminosity than other bright stars such as Canopus,Betelgeuse, orRigel. The system is between 200 and 300 million years old.[18] It was originally composed of two bright bluish stars. The initially more massive of these, Sirius B, consumed its hydrogen fuel and became ared giant before shedding its outer layers and collapsing into its current state as a white dwarf around 120 million years ago.[18]
As the brightest star in the night sky, Sirius appears in some of the earliest astronomical records. Its displacement from theecliptic causes its heliacal rising to be remarkably regular compared to other stars, with a period of almost exactly 365.25 days holding it constant relative to thesolar year. This rising occurs atCairo on 19 July (Julian), placing it just before the onset of theannual flooding of theNile during antiquity.[28] Owing to the flood's own irregularity, the extreme precision of the star's return made it important to theancient Egyptians,[28] who worshipped it as the goddessSopdet (Ancient Egyptian:Spdt, "Triangle";[a]Ancient Greek:Σῶθις},Sō̂this), guarantor of the fertility of their land.[b]
Theancient Greeks observed that the appearance of Sirius as the morning star heralded the hot and dry summer and feared that the star caused plants to wilt, men to weaken, and women to become aroused.[30] Owing to its brightness, Sirius would have been seen totwinkle more in the unsettled weather conditions of early summer. To Greek observers, this signified emanations that caused its malignant influence. Anyone suffering its effects was said to be "star-struck" (ἀστροβόλητος,astrobólētos). It was described as "burning" or "flaming" in literature.[31] The season following the star's reappearance came to be known as the "dog days".[32] The inhabitants of the island ofCeos in theAegean Sea would offer sacrifices to Sirius andZeus to bring cooling breezes and would await the reappearance of the star in summer. If it rose clear, it would portend good fortune; if it was misty or faint then it foretold (or emanated) pestilence. Coins retrieved from the island from the 3rd century BC feature dogs or stars with emanating rays, highlighting Sirius's importance.[31]
The Romans celebrated the heliacal setting of Sirius around 25 April,sacrificing a dog, along with incense, wine, and a sheep, to the goddessRobigo so that the star's emanations would not causewheat rust on wheat crops that year.[33]
Bright stars were important to the ancientPolynesians for navigation of the Pacific Ocean. They also served as latitude markers; the declination of Sirius matches the latitude of the archipelago ofFiji at17°S and thus passes directly over the islands eachsidereal day.[34] Sirius served as the body of a "Great Bird" constellation calledManu, with Canopus as the southern wingtip andProcyon the northern wingtip, which divided the Polynesian night sky into two hemispheres.[35] Just as the appearance of Sirius in the morning sky marked summer in Greece, it marked the onset of winter for theMāori, whose nameTakurua described both the star and the season. Its culmination at thewinter solstice was marked by celebration inHawaii, where it was known asKa'ulua, "Queen of Heaven". Many other Polynesian names have been recorded, includingTau-ua in theMarquesas Islands,Rehua in New Zealand, andTa'urua-fau-papa "Festivity of original high chiefs" andTa'urua-e-hiti-i-te-tara-te-feiai "Festivity who rises with prayers and religious ceremonies" in Tahiti.[36]
In 1717,Edmond Halley discovered theproper motion of the hitherto presumedfixed stars[37] after comparing contemporaryastrometric measurements with those from the second century AD given in Ptolemy'sAlmagest. The bright starsAldebaran,Arcturus and Sirius were noted to have moved significantly; Sirius had progressed about 30arcminutes (about the diameter of the Moon) to the southwest.[38]
In 1868, Sirius became the first star to have its velocity measured, the beginning of the study of celestialradial velocities. SirWilliam Huggins examined thespectrum of the star and observed ared shift. He concluded that Sirius was receding from the Solar System at about 40 km/s.[39][40] Compared to the modern value of −5.5 km/s, this was an overestimate and had the wrong sign; the minus sign (−) means that it is approaching the Sun.[41]
In his 1698 book,Cosmotheoros,Christiaan Huygens estimated the distance to Sirius at 27,664 times thedistance from the Earth to the Sun (about 0.437 light-year, translating to a parallax of roughly 7.5 arcseconds).[42] There were several unsuccessful attempts to measure theparallax of Sirius: byJacques Cassini (6 seconds); by some astronomers (includingNevil Maskelyne)[43] usingLacaille's observations made at theCape of Good Hope (4 seconds); byPiazzi (the same amount); using Lacaille's observations made atParis, more numerous and certain than those made at the Cape (no sensible parallax); byBessel (no sensible parallax).[44]
Scottish astronomerThomas Henderson used his observations made in 1832–1833 and South African astronomerThomas Maclear's observations made in 1836–1837, to determine that the value of the parallax was 0.23 arcsecond, and error of the parallax was estimated not to exceed a quarter of a second, or as Henderson wrote in 1839, "On the whole we may conclude that the parallax of Sirius is not greater than half a second in space; and that it is probably much less."[45] Astronomers adopted a value of 0.25 arcsecond for much of the 19th century.[46] It is now known to have a parallax of nearly0.4 arcseconds.
The Hipparcos parallax for Sirius indicates a distance of8.60 light years, statistically accurate to plus or minus 0.04 light years.[9] Sirius B is generally assumed to be at the same distance. Sirius B has aGaia Data Release 3 parallax with a much smaller statistical margin of error, giving a distance of8.709±0.005 light years, but it is flagged as having a very large value for astrometric excess noise, which indicates that the parallax value may be unreliable.[11]
In a letter dated 10 August 1844, the German astronomerFriedrich Wilhelm Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion.[47] On 31 January 1862, American telescope-maker and astronomerAlvan Graham Clark first observed the faint companion, which is now called Sirius B.[48] This happened during testing of an 18.5-inch (470 mm) aperturegreat refractor telescope forDearborn Observatory, which was one of the largest refracting telescope lenses in existence at the time, and the largest telescope in theUnited States.[49] Sirius B's sighting was confirmed on 8 March with smaller telescopes.[50]
The visible star is now sometimes known as Sirius A. 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 best fit to the data indicates a six-year orbit around Sirius A and a mass of 0.06 M☉. This star would be five to ten magnitudes fainter than the white dwarf Sirius B, which would make it difficult to observe.[51] Observations published in 2008 were unable to detect either a third star or a planet. An apparent "third star" observed in the 1920s is now believed to be a background object.[52]
Twinkling of Sirius (apparent magnitude = −1.5) in the evening shortly before upperculmination on the southernmeridian at a height of 20 degrees above the horizon. During 29 seconds Sirius moves on an arc of 7.5 minutes from the left to the right.
Around the year 150 AD,[57]Claudius Ptolemy of Alexandria, an ethnic Greek Egyptian astronomer of the Roman period, mapped the stars in Books VII and VIII of hisAlmagest, in which he used Sirius as the location for the globe's central meridian.[58] He described Sirius as reddish, along with five other stars,Betelgeuse,Antares,Aldebaran,Arcturus, andPollux, all of which are at present observed to be of orange or red hue.[57] The discrepancy was first noted by amateur astronomerThomas Barker, squire ofLyndon Hall inRutland, who prepared a paper and spoke at a meeting of theRoyal Society in London in 1760.[59] The existence of other stars changing in brightness gave credibility to the idea that some may change in colour too; SirJohn Herschel noted this in 1839, possibly influenced by witnessingEta Carinae two years earlier.[60]Thomas J.J. See resurrected discussion on red Sirius with the publication of several papers in 1892, and a final summary in 1926.[61] He cited not only Ptolemy but also the poetAratus, the oratorCicero, and generalGermanicus all calling the star red, though acknowledging that none of the latter three authors were astronomers, the last two merely translating Aratus's poemPhaenomena.[62]Seneca had described Sirius as being of a deeper red thanMars.[63] It is therefore possible that the description as red is a poetic metaphor for ill fortune. In 1985, German astronomers Wolfhard Schlosser and Werner Bergmann published an account of an 8th-centuryLombardic manuscript, which containsDe cursu stellarum ratio by St. Gregory of Tours. The Latin text taught readers how to determine the times of nighttime prayers from positions of the stars, and a bright star described asrubeola ("reddish") was claimed to be Sirius. The authors proposed this as evidence that Sirius B had been a red giant at the time of observation.[64] Other scholars replied that it was likely St. Gregory had been referring toArcturus.[65][66]
It is notable that not all ancient observers saw Sirius as red. The 1st-century poetMarcus Manilius described it as "sea-blue", as did the 4th-centuryAvienius.[67] Furthermore, Sirius was consistently reported as a white star in ancientChina: a detailed re-evaluation of Chinese texts from the 2nd century BC up to the 7th century AD concluded that all such reliable sources are consistent with Sirius being white.[68][69]
Nevertheless, historical accounts referring to Sirius as red are sufficiently extensive to lead researchers to seek possible physical explanations. Proposed theories fall into two categories: intrinsic and extrinsic. Intrinsic theories postulate a real change in the Sirius system over the past two millennia, of which the most widely discussed is the proposal that the white dwarf Sirius B was a red giant as recently as 2000 years ago. Extrinsic theories are concerned with the possibility of transient reddening in an intervening medium through which the star is observed, such as might be caused by dust in theinterstellar medium, or by particles in theterrestrial atmosphere.
The possibility thatstellar evolution of either Sirius A or Sirius B could be responsible for the discrepancy has been rejected on the grounds that the timescale of thousands of years is orders of magnitude too short and that there is no sign of the nebulosity in the system that would be expected had such a change taken place.[63] Similarly, the presence of a third star sufficiently luminous to affect the visible colour of the system in recent millennia is inconsistent with observational evidence.[70] Intrinsic theories may therefore be disregarded. Extrinsic theories based on reddening byinterstellar dust are similarly implausible. A transient dust cloud passing between the Sirius system and an observer on Earth would, indeed redden the appearance of the star to some degree, but reddening sufficient to cause it to appear similar in colour to intrinsically red bright stars such as Betelgeuse and Arcturus would also dim the star by several magnitudes, inconsistent with historical accounts: indeed, the dimming would be sufficient to render the colour of the star imperceptible to the human eye without the aid of a telescope.[63]
Extrinsic theories based on optical effects in the Earth's atmosphere are better supported by available evidence.Scintillations caused byatmospheric turbulence result in rapid, transient changes in the apparent colour of the star, especially when observed near the horizon, although with no particular preference for red.[71] However, systematic reddening of the star's light results fromabsorption andscattering by particles in the atmosphere, exactly analogous to the redness of the Sun atsunrise andsunset. Because the particles that cause reddening in the Earth's atmosphere are different (typically much smaller) than those that cause reddening in the interstellar medium, there is far less dimming of the starlight, and in the case of Sirius the change in colour can be seen without the aid of a telescope.[63] There may be cultural reasons to explain why some ancient observers might have reported the colour of Sirius preferentially when it was situated low in the sky (and therefore apparently red). In several Mediterranean cultures, the local visibility of Sirius atheliacal rising and setting (whether it appeared bright and clear or dimmed) was thought to have astrological significance and was thus subject to systematic observation and intense interest. Thus Sirius, more than any other star, was observed and recorded while close to the horizon. Other contemporary cultures, such as Chinese, lacking this tradition, recorded Sirius only as white.[63]
Sirius (bottom) and the constellationOrion (right). The three brightest stars in this image—Sirius,Betelgeuse (top right) andProcyon (top left)—form theWinter Triangle. The bright star at top center isAlhena, which forms a cross-shaped asterism with the Winter Triangle.
Sirius can be observed indaylight with the naked eye under the right conditions.[77] Ideally, the sky should be very clear, with the observer at a high altitude, the star passing overhead, and the Sun low on the horizon. These conditions are most easily met around sunset in March and April, and around sunrise in September and October.[78] Observing conditions are more favorable in the Southern Hemisphere, owing to the southerly declination of Sirius.[78]
The orbital motion of the Sirius binary system brings the two stars to a minimum angular separation of 3 arcseconds and a maximum of 11 arcseconds. At the closest approach, it is an observational challenge to distinguish the white dwarf from its more luminous companion, requiring a telescope with at least 300 mm (12 in) aperture and excellent seeing conditions. After aperiastron occurred in 1994,[c]the pair moved apart, making them easier to separate with a telescope.[79]Apoastron occurred in 2019,[d]but from the Earth's vantage point, the greatest observational separation occurred in 2023, with an angular separation of 11.333″.[80]
At a distance of 2.6 parsecs (8.6 ly), the Sirius system contains two of the eightnearest stars to the Sun, and it is the fifth closest stellar system to the Sun.[81] This proximity is the main reason for its brightness, as with other near stars such asAlpha Centauri, Procyon and Vega and in contrast to distant, highly luminous supergiants such as Canopus,Rigel or Betelgeuse (although Canopus may be a bright giant).[82] It is still around 25 times more luminous than the Sun.[18] The closest large neighbouring star to Sirius is Procyon, 1.61 parsecs (5.24 ly) away.[83] TheVoyager 2 spacecraft, launched in 1977 to study the fourgiant planets in the Solar System, is expected to pass within 4.3 light-years (1.3 pc) of Sirius in approximately 296,000 years.[84]
The orbit of Sirius B around A, as seen from Earth (slanted ellipse). The wide horizontal ellipse shows the true shape of the orbit (with an arbitrary orientation) as it would appear if viewed straight on.AChandra X-ray Observatory image of the Sirius star system, where the spike-like pattern is due to the support structure for the transmission grating. The bright source is Sirius B. Credit: NASA/SAO/CXC
Sirius is abinary star system consisting of two white stars orbiting each other with a separation of about 20 AU[e](roughly the distance between the Sun andUranus) and a period of 50.1 years. The brighter component, termed Sirius A, is amain-sequence star ofspectral type early A, with an estimated surface temperature of 9,940 K.[14] Its companion, Sirius B, is a star that has already evolved off the main sequence and become a white dwarf. Currently 10,000 times less luminous in the visual spectrum, Sirius B was once the more massive of the two.[85] The age of the system has been estimated at 230 million years. Early in its life, it is thought to have been two bluish-white stars orbiting each other in an elliptical orbit every 9.1 years.[85] The system emits ahigher than expected level of infrared radiation, as measured byIRAS space-based observatory. This might be an indication of dust in the system, which is considered somewhat unusual for a binary star.[83][86] TheChandra X-ray Observatory image shows Sirius B outshining its partner as an X-ray source.[87]
In 2015, Vigan and colleagues used theVLT 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.[88] Similarly, Lucas and colleagues did not detect any companions around Sirius B.[89]
Comparison of Sirius A and the Sun, to scale and relative surface brightness
Sirius A, also known as the Dog Star, has a mass of 2.063 M☉.[12][18][90] The radius of this star has been measured by anastronomical interferometer, giving an estimated angular diameter of 5.936±0.016 mas. Theprojected rotational velocity is a relatively low 16 km/s,[16] which does not produce any significant flattening of its disk.[91] This is at marked variance with the similar-sizedVega, which rotates at a much faster 274 km/s and bulges prominently around its equator.[92] A weakmagnetic field has been detected on the surface of Sirius A.[93]
Stellar models suggest that the star formed during the collapsing of amolecular cloud and that, after 10 million years, its internal energy generation was derived entirely from nuclear reactions. The core becameconvective and used theCNO cycle for energy generation.[91] It is calculated that Sirius A will have completely exhausted the store of hydrogen at its core within a billion (109) years of its formation, and will then evolve away from the main sequence.[94] It will pass through ared giant stage and eventually become a white dwarf.[95]
Sirius A is classed as a typeAm star, because the spectrum shows deep metallicabsorption lines,[96] indicating an enhancement of its surface layers in elements heavier than helium, such as iron.[83][91] The spectral type has been reported asA0mA1 Va, which indicates that it would be classified as A1 from hydrogen and helium lines, but A0 from the metallic lines that cause it to be grouped with the Am stars.[6] When compared to the Sun, the proportion of iron in the atmosphere of Sirius A relative to hydrogen is given by[15] meaning iron is 316% as abundant as in the Sun's atmosphere. The high surface content of metallic elements is unlikely to be true of the entire star; rather the iron-peak and heavy metals are radiatively levitated towards the surface.[91]
Sirius B (sometimes called "the Pup"[97]) is one of the most massivewhite dwarfs known. With a mass of 1.02 M☉, it is almost double the 0.5–0.6 M☉ average. This mass is packed into a volume roughly equal to the Earth's.[56] The current surface temperature is 25,200 K.[18] Because there is no internal heat source, Sirius B will steadily cool as the remaining heat is radiated into space over the next two billion years or so.[98]
A white dwarf forms after a star has evolved from the main sequence and then passed through ared giant stage. This occurred when Sirius B was less than half its current age, around 120 million years ago. The original star had an estimated 5 M☉[18] and was aB-type star (most likely B5V for 5 M☉)[99][100] when it was still on the main sequence, potentially burning around 600–1200 times more luminous than the sun. While it passed through the red giant stage, Sirius B may have enriched themetallicity of its companion, explaining the very high metallicity of Sirius A.
This star is primarily composed of a carbon–oxygen mixture that was generated by helium fusion in the progenitor star.[18] This is overlaid by an envelope of lighter elements, with the materials segregated by mass because of the high surface gravity.[101] 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.[102]
Although Sirius A and B compose a binary system that is reminiscent of those that can undergoType Ia supernova, the two stars are believed to be too far apart for it to occur, even if Sirius A swells into ared giant.Novas, however, may be possible.[103][better source needed]
"Sirius C" redirects here. For the mythological star, seeEmme Ya.
Since 1894, irregularities have been tentatively observed in the orbits of Sirius A and B with an apparent periodicity of 6–6.4 years. A 1995 study concluded that such a companion likely exists, with a mass of roughly 0.05 solar mass—a smallred dwarf or largebrown dwarf, with an apparent magnitude of more than 15, and less than 3 arcseconds from Sirius A.[51]
In 2017, more accurate astrometric observations by the Hubble Space Telescope ruled out the existence of a stellar mass sized Sirius C, while still allowing a substellar mass candidate such as a lower massBrown dwarf. The 1995 study predicted an astrometric movement of roughly 90 mas (0.09 arcsecond), but Hubble was unable to detect any location anomaly to an accuracy of 5 mas (0.005 arcsec). This ruled out any objects orbiting Sirius A with more than 0.033 solar mass (35 Jupiter masses) in 0.5 years, and 0.014 (15 Jupiter masses) in 2 years. The study was also able to rule out any companions to Sirius B with more than 0.024 solar mass (25 Jupiter masses) orbiting in 0.5 year, and 0.0095 (10 Jupiter masses) orbiting in 1.8 years. Effectively, there are almost certainly no additional bodies in the Sirius system larger than a small brown dwarf or large exoplanet.[104][12]
In 1909,Ejnar Hertzsprung was the first to suggest that Sirius was a member of theUrsa Major Moving Group, based on his observations of the system's movements across the sky. The Ursa Major Group is a set of 220 stars that share a common motion through space. It was once a member of anopen cluster, but has since become gravitationally unbound from the cluster.[105] 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.[18][106][107] Sirius may instead be a member of the proposed Sirius Supercluster, along with other scattered stars such asBeta Aurigae,Alpha Coronae Borealis,Beta Crateris,Beta Eridani andBeta Serpentis.[108] This would be one of three large clusters located within 500 light-years (150 pc) of the Sun. The other two are theHyades and thePleiades, and each of these clusters consists of hundreds of stars.[109]
In 2017, a massive star cluster was discovered only 10 arcminutes from Sirius, making the two appear to bevisually close to one other when viewed from the point of view of theEarth. It was discovered during a statistical analysis ofGaia data. The cluster is over a thousand times further away from us than the star system, but given its size it still appears at magnitude 8.3.[110]
ANeteru image ofSopdet, Egyptian goddess of Sirius and the fertility of theNile, pictured with a star upon her head
The proper name "Sirius" comes from the LatinSīrius, from theAncient GreekΣείριος (Seirios, "glowing" or "scorcher").[111] The Greek word itself may have been imported from elsewhere before theArchaic period,[112] one authority suggesting a link with the Egyptian godOsiris.[113] The name's earliest recorded use dates from the 7th century BC inHesiod's poetic workWorks and Days.[112] In 2016, theInternational Astronomical Union organized aWorking Group on Star Names (WGSN)[114] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[115] included a table of the first two batches of names approved by the WGSN, which includedSirius for the star α Canis Majoris A. It is now so entered in the IAU Catalog of Star Names.[116]
Many cultures have historically attached special significance to Sirius, particularly in relation todogs. It is often colloquially called the "Dog Star" as the brightest star ofCanis Major, the "Great Dog" constellation. Canis Major was classically depicted asOrion's dog. The Ancient Greeks thought that Sirius's emanations could affect dogs adversely, making them behave abnormally during the "dog days", the hottest days of the summer. The Romans knew these days asdies caniculares, and the star Sirius was called Canicula, "little dog". The excessive panting of dogs in hot weather was thought to place them at risk of desiccation and disease. In extreme cases, a foaming dog might have rabies, which could infect and kill humans they had bitten.[31]Homer, in theIliad, describes the approach ofAchilles towardTroy in these words:[123]
Sirius rises late in the dark, liquid sky On summer nights, star of stars, Orion's Dog they call it, brightest Of all, but an evil portent, bringing heat And fevers to suffering humanity.
In a little-attested Greek myth, the star-god that personifiedSirius fell in love with a fertility goddess namedOpora, but he was unable to have her. Thus he began to burn hot, making humans suffer, who prayed to the gods. The god of the north wind,Boreas, solved the problem by ordering his sons to deliver Opora to Sirius, while he cooled down the earth with blasts of his own cold wind.[124][125]
In Iranian mythology, especially inPersian mythology and inZoroastrianism, the ancient religion ofPersia, Sirius appears asTishtrya and is revered as the rain-maker divinity (Tishtar ofNew Persian poetry). Beside passages in thesacred texts of theAvesta, theAvestan languageTishtrya followed by the versionTir inMiddle and New Persian is also depicted in thePersian epicShahnameh ofFerdowsi. Because of the concept of theyazatas, powers which are "worthy of worship", Tishtrya is a divinity of rain and fertility and an antagonist ofapaosha, the demon of drought. In this struggle, Tishtrya is depicted as a white horse.[126][127][128][129]
InChinese astronomy Sirius is known as the star of the "celestial wolf" (Chinese andJapanese: 天狼Chinese romanization: Tiānláng;Japanese romanization: Tenrō;[130] Korean and romanization: 천랑 /Cheonrang) in theMansion of Jǐng (井宿). Many nations among the indigenous peoples ofNorth America also associated Sirius with canines; theSeri andTohono Oʼodham of the southwest note the star as a dog that follows mountain sheep, while theBlackfoot called it "Dog-face". TheCherokee paired Sirius withAntares as a dog-star guardian of either end of the "Path of Souls". ThePawnee of Nebraska had several associations; the Wolf (Skidi) tribe knew it as the "Wolf Star", while other branches knew it as the "Coyote Star". Further north, the AlaskanInuit of theBering Strait called it "Moon Dog".[131]
Several cultures also associated the star with a bow and arrows. The ancient Chinese visualized a large bow and arrow across the southern sky, formed by the constellations ofPuppis and Canis Major. In this, the arrow tip is pointed at the wolf Sirius. A similar association is depicted at theTemple of Hathor inDendera, where the goddessSatet has drawn her arrow atHathor (Sirius). Known as "Tir", the star was portrayed as the arrow itself in later Persian culture.[132]
Sirius is mentioned inSurah,An-Najm ("The Star"), of theQur'an, where it is given the nameالشِّعْرَى (transliteration:aš-ši'rā orash-shira; the leader).[133] The verse is: "وأنَّهُ هُوَ رَبُّ الشِّعْرَى", "That He is the Lord of Sirius (the Mighty Star)." (An-Najm:49)[134]Ibn Kathir said in his commentary "that it is the bright star, named Mirzam Al-Jawza' (Sirius), which a group of Arabs used to worship".[135] The alternate nameAschere, used byJohann Bayer, is derived from this.[19]
Sirius midnight culmination at New Year 2022 local solar time[136]
The midnightculmination of Sirius in the northern hemisphere coincides with the beginning of the New Year[136] of theGregorian calendar during the decades around the year 2000. Over the years, its midnight culmination moves slowly, owing to the combination of the star'sproper motion and theprecession of the equinoxes. At the time of the introduction of the Gregorian calendar in the year 1582, its culmination occurred 17 minutes before midnight into the new year under the assumption of a constant motion. According toRichard Hinckley Allen[138] its midnight culmination was celebrated at theTemple of Demeter at Eleusis.
TheDogon people are anethnic group inMali, West Africa, reported by some researchers to have traditional astronomical knowledge about Sirius that would normally be considered impossible without the use of telescopes. According toMarcel Griaule, they knew about the fifty-year orbital period of Sirius and its companion prior to western astronomers.[139][140]
Doubts have been raised about the validity of Griaule and Dieterlein's work.[141][142] In 1991, anthropologist Walter van Beek concluded about the Dogon, "Though they do speak aboutsigu 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 thesigu [festival], for another it is Venus that, through a different position, appears assigu tolo. All agree, however, that they learned about the star from Griaule."[143] According toNoah Brosch cultural transfer of relatively modern astronomical information could have taken place in 1893, when a French expedition arrived in Central West Africa to observe the total eclipse on 16 April.[144]
In thereligion of theSerer people ofSenegal,the Gambia andMauritania, Sirius is calledYoonir from theSerer language (and some of theCangin language speakers, who are all ethnically Serers). The star Sirius is one of the most important and sacred stars inSerer religious cosmology and symbolism. The Serer high priests and priestesses (Saltigues, the hereditary "rain priests"[147]) chartYoonir to forecast rainfall and enable Serer farmers to start planting seeds. In Serer religious cosmology, it is the symbol of the universe.[145][146]
The position of Sirius on aradar map among all stellar objects orstellar systems within 9 light years (ly) from the map's center, the Sun (Sol). The diamond-shapes are their positions entered according toright ascension inhours angle (indicated at the edge of the map's reference disc), and according to theirdeclination. The second mark shows each's distance from Sol, with theconcentric circles indicating the distance in steps of one ly.
ComposerKarlheinz Stockhausen, who wrote a piece calledSirius, is claimed to have said on several occasions that he came from a planet in the Sirius system.[155][156] To Stockhausen, Sirius stood for "the place where music is the highest of vibrations" and where music had been developed in the most perfect way.[157]
...the fiery Sirius alters hue And bickers into red and emerald.[159]
Throughout the 1990s, several members of the occult group theOrder of the Solar Temple committed mass murder-suicide with the goal of leaving their bodies and spiritually "transiting" to Sirius. In total, 74 people died in all of the suicides and murders.[160]
^Compare the meaning of the Egyptian name with Sirius's completion of theWinter Triangleasterism, joining the other two brightest stars of the northern winter sky,Betelgeuse andProcyon.
^As Sirius is visible together with the constellation ofOrion, the Egyptians worshiped Orion as the godSah, the husband of Sopdet, with whom she had a son, the sky godSopdu. The goddess Sopdet was latersyncretized with the goddessIsis, Sah was linked withOsiris, and Sopdu was linked withHorus. The joining of Sopdet with Isis would allowPlutarch to state that "The soul of Isis is called Dog by the Greeks", meaning Sirius worshiped as Isis-Sopdet by Egyptians was named the Dog by the Greeks and Romans. The 70 day period of the absence of Sirius from the sky was understood as the passing of Sopdet-Isis and Sah-Osiris through theEgyptian underworld.[29]
^Two full 50.09 year orbits following the periastron epoch of 1894.13 gives a date of 1994.31.
^Two and one-half 50.09 year orbits following the periastron epoch of 1894.13 gives a date of 2019.34 .
^Semi-major axis in AU =semimajor axis in seconds/ parallax =7.56″/0.37921 = 19.8 AU; as the eccentricity is 0.6, the distance fluctuates between 40% and 160% of that, roughly from 8 AU to 32 AU.
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^Singh, Nagendra Kumar (2002).Encyclopaedia of Hinduism, A Continuing Series. Anmol Publications PVT. LTD. p. 794.ISBN81-7488-168-9.
^Spahn, Mark; Hadamitzky, Wolfgang; Fujie-Winter, Kimiko (1996).The Kanji dictionary. Tuttle language library. Tuttle Publishing. p. 724.ISBN0-8048-2058-9.
^"Sirius A".SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved20 October 2007.
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^Aitken, R. G. (1942). "Edmund Halley and Stellar Proper Motions".Astronomical Society of the Pacific Leaflets.4 (164):103–112.Bibcode:1942ASPL....4..103A.
^Daintith, John; Mitchell, Sarah; Tootill, Elizabeth; Gjertsen, D. (1994).Biographical Encyclopedia of Scientists. CRC Press. p. 442.ISBN0-7503-0287-9.
^Huggins, W. (1868). "Further observations on the spectra of some of the stars and nebulae, with an attempt to determine therefrom whether these bodies are moving towards or from the Earth, also observations on the spectra of the Sun and of Comet II".Philosophical Transactions of the Royal Society of London.158:529–564.Bibcode:1868RSPT..158..529H.doi:10.1098/rstl.1868.0022.
^abBenest, D.; Duvent, J. L. (July 1995). "Is Sirius a triple star?".Astronomy and Astrophysics.299:621–628.Bibcode:1995A&A...299..621B. – For the instability of an orbit around Sirius B, see § 3.2.
^Holberg, J. B. (2005). "How Degenerate Stars Came to be Known as White Dwarfs".Bulletin of the American Astronomical Society.37 (2): 1503.Bibcode:2005AAS...20720501H.
^Hanbury Brown, R.; Twiss, R. Q. (1958). "Interferometry of the Intensity Fluctuations in Light. IV. A Test of an Intensity Interferometer on Sirius A".Proceedings of the Royal Society of London.248 (1253):222–237.Bibcode:1958RSPSA.248..222B.doi:10.1098/rspa.1958.0240.S2CID124546373.
^Kuchner, Marc J.; Brown, Michael E. (2000). "A Search for Exozodiacal Dust and Faint Companions Near Sirius, Procyon, and Altair with the NICMOS Coronagraph".Publications of the Astronomical Society of the Pacific.112 (772):827–832.arXiv:astro-ph/0002043.Bibcode:2000PASP..112..827K.doi:10.1086/316581.S2CID18971656.
^Espenak, Fred."Mars Ephemeris".Twelve Year Planetary Ephemeris: 1995–2006, NASA Reference Publication 1349. Archived fromthe original on 17 February 2013.
^abHenshaw, C. (1984). "On the Visibility of Sirius in Daylight".Journal of the British Astronomical Association.94 (5):221–222.Bibcode:1984JBAA...94..221H.
^Backman, D. E. (30 June – 11 July 1986). "IRAS observations of nearby main sequence stars and modeling of excess infrared emission". In Gillett, F. C.; Low, F. J. (eds.).Proceedings, 6th Topical Meetings and Workshop on Cosmic Dust and Space Debris. Vol. 6. Toulouse, France: COSPAR and IAF. pp. 43–46.Bibcode:1986AdSpR...6...43B.doi:10.1016/0273-1177(86)90209-7.ISSN0273-1177.
^Imamura, James N. (2 October 1995)."Cooling of White Dwarfs". University of Oregon. Archived fromthe original on 15 December 2006. Retrieved3 January 2007.
^Siess, Lionel (2000)."Computation of Isochrones". Institut d'Astronomie et d'Astrophysique, Université libre de Bruxelles. Retrieved24 March 2007.
^Palla, Francesco (16–20 May 2005). "Stellar evolution before the ZAMS".Proceedings of the international Astronomical Union 227. Italy: Cambridge University Press. pp. 196–205.Bibcode:1976IAUS...73...75P.
^Holberg, J. B.; Barstow, M. A.; Burleigh, M. R.; Kruk, J. W.; Hubeny, I.; Koester, D. (2004). "FUSE observations of Sirius B".Bulletin of the American Astronomical Society.36: 1514.Bibcode:2004AAS...20510303H.
^"Sirius". Britannica Online Encyclopedia. 2007. Retrieved10 September 2007.
^"An-Najm (The Star), Surah 53".Translations of the Qur'an. University of Southern California, Center for Muslim-Jewish Engagement. 2007. Archived fromthe original on 19 February 2009. Retrieved8 August 2009.
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^Allen, Richard Hinckley (1899).Star-names and Their Meanings. G.E. Stechert. p. 125.The culmination of this star at midnight was celebrated in the great temple of Ceres at Eleusis
^Griaule, Marcel (1965).Conversations with Ogotemmeli: An Introduction to Dogon Religious Ideas. International African Institute.ISBN0-19-519821-2. (many reprints) Originally published in 1948 as Dieu d'Eau.
^Griaule, Marcel; Dieterlen, Germaine (1965).The Pale Fox. Institut d'Ethnologie. Originally published as Le Renard Pâle.
^van Beek, W. A. E.; Bedaux; Blier; Bouju; Crawford; Douglas; Lane; Meillassoux (1991). "Dogon Restudied: A Field Evaluation of the Work of Marcel Griaule".Current Anthropology.32 (2):139–167.doi:10.1086/203932.JSTOR2743641.S2CID224796672.
^abGravrand, Henry, "La civilisation sereer :Pangool", vol. 2, Les Nouvelles Editions Africaines du Sénégal, (1990) pp. 20–21, 149–155,ISBN2-7236-1055-1.
^abClémentine Faïk-Nzuji Madiya, Canadian Museum of Civilization, Canadian Centre for Folk Culture Studies, International Centre for African Language, Literature and Tradition (Louvain, Belgium).ISBN0-660-15965-1. pp. 5, 27, 115.
^Galvan, Dennis Charles,The State Must be our Master of Fire : How Peasants Craft Culturally Sustainable Development in Senegal, Berkeley, University of California Press, (2004), pp. 86–135,ISBN978-0-520-23591-5.
^"Mitsubishi Motors history".Mitsubishi Motors – South Africa Official Website. Mercedes Benz. 2007. Archived fromthe original on 30 December 2007. Retrieved27 January 2008.
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