Sirius

The Ancient Greeks also thought that Sirius emanations could affect dogs adversely, making them behave abnormally in the heat of summer ( Dog Days --the Romans knew these days as dies caniculares and the star as Canicula, little dog ). The authors proposed this was further evidence Sirius B had been a red giant at the time. The possibility that stellar evolution of either Sirius A or Sirius B could be responsible for this discrepancy has been rejected by astronomers on the grounds that the timescale of thousands of years is too short and that there is no sign of the nebulosity in the system that would be expected had such a change taken place. With an apparent magnitude of −1.46, Sirius is the brightest star in the night sky, almost twice the brightness of the second brightest star, Canopus. Sirius can even be observed in daylight with the naked eye under the right conditions.

They also refer to a third star accompanying Sirius A and B. Sir William Huggins examined the spectrum of this star and observed a noticeable red shift.

Low on the horizon, they acted as stellar compasses to assist mariners in charting courses to particular destinations. This occurred just before the annual flooding of the Nile and the summer solstice, The Ancient Greeks believed that the appearance of Sirius heralded the hot and dry summer, and feared its effects on making plants wilt, men weaken and women become aroused. Ptolemy of Alexandria mapped the stars in Book VII and VIII of his Almagest, in which he used Sirius as the location for the globe s central meridian.

At a distance of 2.6 parsecs (8.6 light years), the Sirius system is one of our near neighbors. The core became convective and utilized the CNO cycle for energy generation.

At this point it will pass through a red giant stage, then settle down to become a white dwarf. The spectrum of Sirius A shows deep metallic lines, indicating an enhancement in elements heavier than helium, such as iron. With a mass nearly equal to the Sun s, Sirius B is one of the more massive white dwarfs known; it is almost double the 0.5–0.6 solar mass average. What the naked eye perceives as a single star is actually a binary star system, consisting of a white main sequence star of spectral type A1V, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. Sirius appears bright due to both its intrinsic luminosity and its closeness to the Earth.

Ideally, the sky should be very clear, with the observer at a high altitude, the star passing overhead, and the sun low down on the horizon. 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. The Latin text taught readers how to determine the times of nighttime prayers from positions of the stars, and Sirius is described within as rubeola reddish .

Sirius is the brightest star in the night sky, with a visual apparent magnitude of −1.46, almost twice as bright as Canopus, the next brightest star. Gregory of Tours.

The other five are class M and K stars, such as Arcturus and Betelgeuse. Bright stars were important to the ancient Polynesians for navigation between the many islands and atolls of the Pacific Ocean. 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.

Homer, in the Iliad, describes the approach of Achilles toward Troy in those very terms: 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 Chinese astronomy the star is known as the star of the celestial wolf (Chinese: 天狼; Korean: 천랑 j=天狼; Chinese romanization: Tiānláng; Korean romanization: Cheonlang, Japanese romanization: Tenrō; Several cultures also associated the star with a bow and arrows. This occurred when Sirius B was less than half its current age, approximately 120 million years ago.

Sirius A is about twice as massive as the Sun and has an absolute visual magnitude of 1.42. The name Sirius is derived from the Ancient Greek Σείριος.

Their excessive panting was thought to place them at risk of desiccation and disease. It was also classically depicted as Orion s dog.

Yet that same mass is packed into a volume roughly equal to the Earth. The original star had an estimated 5 solar masses when it still was on the main sequence.

Robert Temple s 1976 book The Sirius Mystery, credits them with knowledge of the four Galilean moons of Jupiter and the rings of Saturn. The current surface temperature is 25,200 K. A white dwarf forms only after the star has evolved from the main sequence and then passed through a red giant stage.

The Ursa Major Group is a set of 220 stars that share a common motion through space and were once formed as members of an open cluster, which has since become gravitationally unbound. The most commonly used proper name of this star comes from the Latin Sīrius, from the Ancient Greek Σείριος (Seirios, glowing or scorcher ), Many cultures have historically attached special significance to Sirius, particularly in relation to dogs. However, it is notable for introducing the study of celestial radial velocities. In 1844 German astronomer Friedrich Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion. In 1915, Walter Sydney Adams, using a 60-inch (1.5 meter) reflector at Mount Wilson Observatory, observed the spectrum of Sirius B and determined that it was a faint whitish star. In 150 AD, the astronomer Ptolemy described Sirius as reddish, along with five other stars, Betelgeuse, Antares, Aldebaran, Arcturus and Pollux, all of which are clearly of orange or red hue. 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.

According to a 1978 Skeptical Enquirer article it is possibly the result of cultural contamination. Sirius is frequently a subject used in science fiction and related popular culture. Seven ships of the Royal Navy have been called HMS Sirius since the 18th century, with the first being the flagship of the First Fleet to Australia in 1788. Sirius is one of the 27 stars on the flag of Brazil, where it represents the state of Mato Grosso. Coordinates: 06h 45m 08.9173s, −16° 42′ 58.017″ . In extreme cases, a foaming dog may have rabies, which could infect and kill humans who d been bitten.

It is predicted that Sirius A will have completely exhausted the store of hydrogen at its core within a billion (109) years of its formation. The star has the Bayer designation α Canis Majoris (α CMa, or Alpha Canis Majoris).

From there is it sent via the Sun to the god of Earth (Sanat Kumara), and finally through the seven Masters of the Seven Rays to the human race. The Dogon people are an ethnic group in Mali, West Africa, reported to have traditional astronomical knowledge about Sirius that would normally be considered impossible without the use of telescopes. While it passed through the red giant stage, Sirius B may have enriched the metallicity of its companion. This star is primarily composed of a carbon-oxygen mixture that was generated by helium fusion in the progenitor star. 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.

According to Marcel Griaule s books Conversations with Ogotemmêli and The Pale Fox they knew about the fifty-year orbital period of Sirius and its companion prior to western astronomers. Indeed, it is often colloquially called the Dog Star as the brightest star of Canis Major, the Great Dog constellation.

A periastron occurred in 1994 At a distance of 2.6 parsecs or 8.6 light years, the Sirius system contains two of the eight nearest stars to the Solar System Sirius is a binary star system consisting of two white stars orbiting each other with a separation of about 20 astronomical units Sirius A has a mass of around 2.1 times that of the Sun. Stellar models suggest that the star formed during the collapsing of a molecular cloud, and that after 10 million years, its internal energy generation was derived entirely from nuclear reactions. He concluded that Sirius was receding from the Solar System at about 40 km/s.

The heliacal rising of Sirius marked the flooding of the Nile in Ancient Egypt and the Dog Days of summer for the Ancient Greeks, while to the Polynesians it marked winter and was an important star for navigation around the Pacific Ocean. Hieroglyph of Sirius/Sopdet Sirius, known in Ancient Egypt as Sopdet (Greek: Sothis), is recorded in the earliest astronomical records. this both was an overestimate and had the wrong sign; the minus means it is approaching our Sun.

Known as Tir, the star was portrayed as the arrow itself in later Persian culture. Sirius is mentioned in Surah (chapter) 53 of the Qur an titled An-Najm ( The Star ). In this, the arrow tip is pointed at the wolf Sirius.

A similar association is depicted at the Temple of Hathor in Dendera, where the goddess Satet has drawn her arrow at Hathor (Sirius). They also served as latitude markers; the declination of Sirius matches the latitude of the island of Fiji at 17°S and thus passes directly over the island each night. In 1718, Edmond Halley discovered the proper motion of the hitherto presumed fixed stars In 1868, Sirius became the first star to have its velocity measured.

He curiously depicted it as one of six red-coloured stars (see the Red controversy section below). It is 25 times more luminous than the Sun Sirius is also known colloquially as the Dog Star , reflecting its prominence in its constellation, Canis Major (English: Big Dog).

During the era of the Middle Kingdom, Egyptians based their calendar on the heliacal rising of Sirius, namely the day it becomes visible just before sunrise after moving far enough away from the glare of the sun. It is mentioned by name: That He is the Lord of Sirius (the Mighty Star). (53:49) In Theosophy, it is believed the Seven Stars of the Pleiades transmit the spiritual energy of the Seven Rays from the Galactic Logos to the Seven Stars of the Great Bear, then to Sirius.

The Ancient Chinese visualized a large bow and arrow across the southern sky, formed by the constellations of Puppis and Canis Major. This has been the subject of controversy and speculation.