Тукан: Созвездие Южного Неба

Constellation in the southern celestial hemisphere

Tucana (The Toucan) is a constellation of stars in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Tucana first appeared on a celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Tucana, Grus, Phoenix and Pavo are collectively known as the "Southern Birds". Tucana is not a prominent constellation as all of its stars are third magnitude or fainter; the brightest is Alpha Tucanae with an apparent visual magnitude of 2.87. Beta Tucanae is a star system with six member stars, while Kappa is a quadruple system. Five star systems have been found to have exoplanets to date. The constellation contains 47 Tucanae, one of the brightest globular clusters in the sky, and most of the Small Magellanic Cloud.

Tucana is one of the twelve constellations established by the astronomer Petrus Plancius from the observations of the southern sky by the Dutch explorers Pieter Dirkszoon Keyser and Frederick de Houtman, who had sailed on the first Dutch trading expedition, known as the Eerste Schipvaart, to the East Indies. It first appeared on a celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in the German cartographer Johann Bayer's Uranometria of 1603. Both Plancius and Bayer depict it as a toucan. by this meaning a particular bird with a long beak—a hornbill, a bird native to the East Indies. A 1603 celestial globe by Willem Blaeu depicts it with a casque. It was interpreted on Chinese charts as Niǎohuì "bird's beak", and in England as "Brasilian Pye", while Johannes Kepler and Giovanni Battista Riccioli termed it Anser Americanus "American Goose", and Caesius as Pica Indica. Tucana and the nearby constellations Phoenix, Grus and Pavo are collectively called the "Southern Birds".

Irregular in shape, Tucana is bordered by Hydrus to the east, Grus and Phoenix to the north, Indus to the west and Octans to the south. Covering 295 square degrees, it ranks 48th of the 88 constellations in size. The recommended three letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Tuc".

Although he depicted Tucana on his chart, Bayer did not assign its stars Bayer designations. French explorer and astronomer Nicolas Louis de Lacaille labelled them Alpha to Rho in 1756, but omitted Omicron and Xi, and labelled a pair of stars close together Lambda Tucanae, and a group of three stars Beta Tucanae. In 1879, American astronomer Benjamin Gould designated a star Xi Tucanae—this had not been given a designation by Lacaille who had recognized it as nebulous, and it is now known as the globular cluster 47 Tucanae. Mu Tucanae was dropped by Francis Baily, who felt the star was too faint to warrant a designation, and Kappa's two components came to be known as Kappa1 and Kappa2. The layout of the brighter stars of Tucana has been likened to a kite. Within the constellation's boundaries are around 80 stars brighter than an apparent magnitude of 7. At an apparent magnitude of 2.86, Alpha Tucanae is the brightest star in the constellation and marks the toucan's head. Alpha Tucanae is a spectroscopic binary, which means that the two stars have not been individually resolved using a telescope, but the presence of the companion has been inferred from measuring changes in the spectrum of the primary. The orbital period of the binary system is 4197.7 days (11.5 years). Nothing is known about the companion. It is classified as a semiregular variable star and its brightness varies from magnitude +4.75 to +4.93. Described by Richard Hinckley Allen as bluish, It also marks the toucan's beak. Beta, Delta and Kappa are multiple star systems containing six, two and four stars respectively. Located near the tail of the toucan, Lying in the southwestern corner of the constellation around 251 light years away from Earth, Delta Tucanae consists of a blue white primary contrasting with a yellowish companion. The companion has an apparent magnitude of 9.3. The Kappa Tucanae system shines with a combined apparent magnitude of 4.25, and is located around 68 light years from the Solar System. The brighter component is a yellowish star, while the fainter lies 5 arcseconds to the northwest. Five arcminutes to the northwest is a fainter star of apparent magnitude 7.24—actually a pair of orange main sequence stars of spectral types K2V and K3V, which can be seen individually as stars one arcsecond apart with a telescope such as a Dobsonian with high power. and a yellow main sequence star of spectral type G1V and an apparent magnitude of 7.28. The system is 186 light years distant. Epsilon Tucanae traditionally marks the toucan's left leg. It is around four times as massive as the Sun. Theta Tucanae is a white A type star around 423 light years distant from Earth, which is actually a close binary system. The main star is classified as a Delta Scuti variable—a class of short period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study asteroseismology. It is around double the Sun's mass, having siphoned off one whole solar mass from its companion, now a hydrogen depleted dwarf star of around only 0.2 solar masses. The system shines with a combined light that varies between magnitudes 6.06 to 6.15 every 70 to 80 minutes. Zeta Tucanae is a yellow white main sequence star of spectral type F9.5V and an apparent magnitude of 4.20 located 28 light years away from the Solar System. Despite having a slightly lower mass, this star is more luminous than the Sun. The composition and mass of this star are very similar to the Sun, with a slightly lower mass and an estimated age of three billion years. The solar like qualities make it a target of interest for investigating the possible existence of a life bearing planet. It appears to have a debris disk orbiting it at a minimum radius of 2.3 astronomical units. As of 2009, no planet has been discovered in orbit around this star. Five star systems have been found to have planets, four of which have been discovered by the High Accuracy Radial Velocity Planet Searcher (HARPS) in Chile. HD 4308 is a star with around 83% of the Sun's mass located 72 light years away with a super Earth planet with an orbital period of around 15 days. HD 215497 is an orange star of spectral type K3V around 142 light years distant. It is orbited by a hot super Earth every 3 days and a second planet around the size of Saturn with a period of around 567 days. HD 221287 has a spectral type of F7V and lies 173 light years away, and has a super Jovian planet. HD 7199 has spectral type KOIV/V and is located 117 light years away. It has a planet with around 30% the mass of Jupiter that has an orbital period of 615 days. HD 219077 has a planet around 10 times as massive as Jupiter in a highly eccentric orbit.

The second brightest globular cluster in the sky after Omega Centauri, 47 Tucanae (NGC 104) lies just west of the Small Magellanic Cloud. Only 14,700 light years distant from Earth, it is thought to be around 12 billion years old.]] Located at the southern end of Tucana, the Small Magellanic Cloud is a dwarf galaxy that is one of the nearest neighbors to the Milky Way galaxy at a distance of 210,000 light years. Though it probably formed as a disk shape, tidal forces from the Milky Way have distorted it. Along with the Large Magellanic Cloud, it lies within the Magellanic Stream, a cloud of gas that connects the two galaxies. NGC 346 is a star forming region located in the Small Magellanic Cloud. It has an apparent magnitude of 10.3. The Tucana Dwarf galaxy, which was discovered in 1990, is a dwarf spheroidal galaxy of type dE5 that is an isolated member of the Local Group. It is located from the Solar System and around from the barycentre of the Local Group—the second most remote of all member galaxies after the Sagittarius Dwarf Irregular Galaxy. The barred spiral galaxy NGC 7408 is located 3 degrees northwest of Delta Tucanae, and was initially mistaken for a planetary nebula.