Tucana constellation lies in the southern hemisphere. It represents the toucan, a bird found in tropical and sub-tropical regions.
The constellation was introduced by the Dutch astronomer Petrus Plancius from the observations of Dutch sailors Frederick de Houtman and Pieter Dirkszoon Keyser in the late 16th century. It was first depicted in a celestial atlas in 1603, in Johann Bayer’s Uranometria.
The constellation is home to the Tucana Dwarf galaxy, the Small Magellanic Cloud, the globular cluster 47 Tucanae, and several other notable deep sky objects.
Facts, location and map
Tucana is the 48th constellation in size, occupying an area of 295 square degrees. It lies in the first quadrant of the southern hemisphere (SQ1) and can be seen at latitudes between +25° and -90°. The neighboring constellations are Eridanus, Grus, Hydrus, Indus, Octans and Phoenix.
Tucana contains three stars with known planets and no Messier objects. The brightest star in the constellation is Alpha Tucanae, with an apparent magnitude of 2.86. There are no meteor showers associated with the constellation.
Tucana contains two formally named stars. The star names approved by the International Astronomical Union (IAU) are Emiw and Poerava.
Tucana is not associated with any myths. The constellation’s name is Latin for “the toucan,” a South American bird with a huge bill. The Dutch astronomer and cartographer Petrus Plancius first depicted the constellation on a celestial globe in 1598 and gave it the name Tucana.
Johann Bayer kept the name in his atlas of 1603, but Frederick de Houtman called the constellation Den Indiaenschen Exster, op Indies Lang ghenaemt, which means “the Indian magpie, named Lang in the Indies,” in his 1603 catalogue. Presumably, de Houtman was describing the hornbill, a different bird that is also native to the East Indies and Malaysia. In the end, the name Tucana won out.
α Tucanae (Alpha Tucanae)
Alpha Tucanae is the brightest star in the constellation. It has an apparent magnitude of 2.86 and is approximately 200 light years distant from the Sun.
It is a spectroscopic binary system with a period of 11.5 years. The primary star is an orange giant belonging to the stellar class K3 III.
γ Tucanae (Gamma Tucanae)
Gamma Tucanae is a yellow-white giant with the stellar classification of F1 III. It is the second brightest star in Tucana. It has an apparent magnitude of 3.99 and is 75.3 light years distant from the solar system. It is 1.55 times more massive than the Sun.
ζ Tucanae (Zeta Tucanae)
Zeta Tucanae is the third brightest star in the constellation. It is a yellow-white main sequence dwarf belonging to the spectral class F9.5V. It has an apparent magnitude of 4.23 and is 28.01 light years distant from Earth.
The star has 99 percent of the Sun’s mass, 108 percent of the solar radius, and is 1.26 times more luminous than the Sun. It emits excess infrared radiation, which indicates that it has a debris disk in its orbit. The star’s estimated age is about 3 billion years.
κ Tucanae (Kappa Tucanae)
Kappa Tucanae is a multiple star system in Tucana. It has a combined apparent magnitude of 4.25 and is 66.6 light years distant.
The Kappa Tucanae system is composed of two binary pairs separated by 5.3 minutes of arc. The primary component is a yellow-white subgiant star with the stellar classification of F6IV and a visual magnitude of 5.1. Its binary companion is located 5 arc seconds away and has an apparent magnitude of 7.3. The two stars have an orbital period of 1,222 years.
The other binary star in the system consists of a magnitude 7.8 and a magnitude 8.2 star separated by 1.12 arc seconds. The pair has an orbital period of 86.2 years.
β Tucanae (Beta Tucanae)
The Bayer designation Beta Tucanae refers to a group of six stars in Tucana that are loosely bound into a star system. The system is approximately 140 light years distant from the Sun. The brightest two components have visual magnitudes of 4.36 and 4.53. They are a blue-white dwarf and a white dwarf separated by 27 arc seconds. The brighter component has a magnitude 13.5 star for a companion, and the secondary component has a 6th magnitude companion. Both companions are white main sequence stars.
The system also contains a binary star separated from the two brightest components by 9 arc minutes. The binary system consists of two white main sequence dwarfs with apparent magnitudes of 5.8 and 6.0. The stars are separated by 0.1 arc seconds.
ε Tucanae (Epsilon Tucanae)
Epsilon Tucanae is a blue-white subgiant with the stellar classification of B9IV. It has a visual magnitude of 4.49 and is approximately 374 light years distant from the Sun.
δ Tucanae (Delta Tucanae)
Delta Tucanae is a binary system with an apparent magnitude of 4.51. It is about 267 light years distant from Earth.
The primary star is a blue-white dwarf belonging to the spectral class B9.5V. The companion is located 7 arc seconds away and has an apparent magnitude of 9.3.
ν Tucanae (Nu Tucanae)
Nu Tucanae is a red giant with the stellar classification M4III. It has a mean apparent magnitude of 4.91 and is approximately 273 light years distant from the Sun. It is an irregular variable star exhibiting variations in magnitude ranging from 4.75 to 4.93.
ι Tucanae (Iota Tucanae)
Iota Tucanae is a yellow giant belonging to the stellar class G5III. It is a semi-regular variable star and its brightness varies by 0.06 magnitudes. It has a visual magnitude of 5.36 and is approximately 279 light years distant from the solar system.
HD 219077 is a yellow main sequence dwarf with the stellar classification of G8V. It has an apparent magnitude of 6.12 and is 95.2 light years distant from Earth. The star has roughly the same mass as the Sun and 1.91 times the solar radius. It is 2.66 times more luminous than the Sun.
A planet was discovered orbiting the star in 2012. It has a mass at least 10.39 times that of Jupiter and orbits the star with a period of 5,501 days.
HD 4308 is another yellow dwarf with a confirmed planet. It has the stellar classification of G6V and an apparent magnitude of 6.54. The star is 71.9 light years distant from the Sun. It has 83 percent of the Sun’s mass and 92 percent of the solar radius.
The planet has a mass at least 0.0442 times that of Jupiter and it completes an orbit around the star every 15.56 days.
HD 221287 is a yellow-white dwarf with the stellar classification of F7V. It has a visual magnitude of 7.82 and is 172.5 light years distant from the solar system.
A planet with a minimum mass of 3.12 times that of Jupiter was discovered orbiting the star in March 2007. It completes an orbit every 456.1 days.
HD 215497 is an orange dwarf star belonging to the spectral class K3V. It has an apparent magnitude of 8.96 and is approximately 142 light years distant from Earth. The star has 87.2 percent of the Sun’s mass, about the same radius, and only 39 percent of the Sun’s luminosity.
Two planets, both less massive than Jupiter, were discovered orbiting the star in 2009. The inner planet has a mass at least 6.6 times that of the Earth and orbits the star every 3.93404 days. The outer planet has at least 0.33 times the mass of Jupiter, which makes it roughly the same size as Saturn, and an orbital period of 567.94 days.
HD 5980 is a star located in the open cluster NGC 346 and the brightest object in the Small Magellanic Cloud. It is in fact one of the most luminous stars known. It has an apparent magnitude of 11.31 and a combined absolute magnitude of -7.3. The star is approximately 200,000 light years distant from the solar system.
HD 5980 consists of three components and all three are among the luminous stars known. The primary component in the system is a Wolf-Rayet star that has produced a luminous blue variable eruption. Wolf-Rayet stars are evolved, exceptionally hot, highly luminous and very massive stars that are rapidly losing mass as a result of a strong stellar wind. The secondary component is also a Wolf-Rayet star and forms an eclipsing spectroscopic binary with the primary star. The stars have an orbital period of 19 days. The third component in the system is a blue, class O supergiant which may not be physically associated with the other two stars and may itself be a close binary.
The Wolf-Rayet stars have masses 58-79 times (component A) and 51-67 times (component B) solar. The primary star is 2 million times more luminous than the Sun, as is the blue supergiant, while the secondary component has 2.5 million solar luminosities.
Deep sky objects in Tucana
The Tucana Dwarf is a dwarf spheroidal galaxy with an apparent magnitude of 15.7. It is approximately 3.2 million light years distant from Earth. The galaxy was discovered by R. J. Lavery in 1990.
The Tucana Dwarf contains only very old stars and has no galactic neighbours. Unlike other isolated dwarf galaxies, it is not experiencing any star forming activity.
Small Magellanic Cloud
The Small Magellanic Cloud is a dwarf galaxy usually classified either as a dwarf irregular galaxy or a Magellanic type dwarf spiral galaxy. It is a companion galaxy to the Milky Way and a member of the Local Group of galaxies. It has an apparent magnitude of 2.7 and is approximately 197,000 light years distant from the solar system. The galaxy is one of the most distant deep sky objects that can be seen without binoculars.
The Small Magellanic Cloud contains several hundred million stars. It has a central bar structure. It is possible that it used to be a barred spiral galaxy once, but its structure was interrupted by interactions with the Milky Way.
SMC can only be seen from the southern hemisphere and lower northern latitudes. It appears as a patch of light spanning about 3 degrees.
The galaxy forms a pair with the Large Magellanic Cloud, located about 20 degrees to the east, in the constellations Dorado and Mensa. The two galaxies are connected by a bridge of gas and believed to be tidally interacting. The bridge is a site of intense star formation. There is evidence that suggests that the two galaxies have been gravitationally bound for a long time.
NGC 346 is an open star cluster associated with a nebula in the Small Magellanic Cloud. The cluster contains the luminous star HD 5980.
NGC 104 – 47 Tucanae
NGC 104 is a globular cluster in Tucana. It has an apparent magnitude of 4.91 and is approximately 16,700 light years distant from Earth. The cluster is about 120 light years across, has a very bright and dense core, and can be seen without binoculars. It is the second brightest globular cluster in the night sky, after Omega Centauri in Centaurus constellation.
NGC 104 was discovered by the French astronomer Nicolas Louis de Lacaille in 1751 while he was mapping the southern skies in South Africa.
The cluster contains millions of stars and is one of the most massive globular clusters known in the Milky Way.
NGC 406 is a spiral galaxy in Tucana constellation. It is approximately 60,000 light years across and about 65 million light years distant from Earth. It resembles the more famous Whirlpool Galaxy in Canes Venatici constellation.
NGC 362 is a globular cluster. It has an apparent magnitude of 6.4 and is approximately 27,700 light years distant from Earth.
The cluster was discovered by the Scottish astronomer James Dunlop on August 1, 1826. It is quite bright and can be seen in a small telescope.
NGC 248 is an emission nebula in Tucana. It was discovered by the English astronomer John Herschel in on April 11, 1834.
NGC 265 is an open cluster located in the Small Magellanic Cloud. It is approximately 200,000 light years distant from the solar system. The cluster is about 32 light years in radius.
NGC 290 is another open cluster in the Small Magellanic Cloud. It is 65 light years across.