Tucana is a small, dim constellation of the southern skies that is one of 12 created by Petrus Plancius in the late 16th-century, based upon the observations of Dutch explorers Pieter Dirkszoon Keyser and Frederick de Houtman. The constellation is named after “the toucan” bird, and is a member of the “Southern Birds” group of constellations, together with Grus (“crane”), Pavo (“peacock”), and Phoenix. The brightest star in Tucana, Alpha Tucanae, is a binary system located 200 light years distant with an apparent visual magnitude of 2.86.
Tucana is the 48th largest constellation, and takes up an area of 295 square degrees of the southern celestial sphere. It can be viewed by observers located between +25° and -90° of latitude, and is best seen during the months of August and October. Bordering Tucana is the constellations of Hydrus (east), Grus and Phoenix (north), Indus (west) and Octans (south).
Johann Bayer Family
Tucana belongs to the Johann Bayer constellations family, along with Apus, Chamaeleon, Dorado, Grus, Hydrus, Indus, Musca, Pavo, Phoenix and Volans.
– Alpha Tucanae, the constellation’s brightest star, is a binary system, found 200 light years from our solar system that shines with an apparent magnitude of 2.85. Its primary component is an orange giant (K3 III) that is 37 times bigger than the Sun, with 3 times its mass, and 424 times its luminosity. The binary system has an orbital period of 11.5 years.
– Gamma Tucanae, the second brightest star in Tucana, is a yellow-white (F1 III) located 75 light years from Earth with a visual magnitude of 3.99. It is almost twice the size of the Sun, and marks the celestial toucan’s beak.
– Zeta Tucanae, the constellation’s third brightest star, is a yellow-white dwarf (F9.5V) situated 28 light year away of magnitude 4.23. This 3 billion year old star is similar in size and mass to our sun, but has around 24% more luminosity.
Other stars of interest in Tucan includes the multiple stars systems of Beta Tucanae, Kappa Tucanae, and Delta Tucanae; the blue-white subgiant Epsilon Tucanae; the yellow giant Iota Tucanae; the yellow dwarf stars HD 219077, HD 4308, and HD 221287; the orange dwarf HD 215497; and the red giant star Nu Tucanae.
Notable Deep-Sky Objects
The constellation contains no Messier objects, but there are a number of deep-sky objects of interest to astronomers.
– 47 Tucanae (NGC 104) has a visual magnitude of 4.91, making it the night sky’s second brightest globular cluster after Omega Centauri (NGC 5139) in the constellation of Centaurus. The cluster is around 120 light years wide, 16,700 light years distant, and contains millions of stars, including blue stragglers, cataclysmic variable stars, and millisecond pulsars.
Other deep-sky objects of interest in the constellation includes Tucana Dwarf, an isolated dwarf galaxy containing very old stars that is 3.2 million light years distant, and shines with an apparent magnitude of 15.7. In Tucana can also be found the open star clusters NGC 346, NGC 265, and NGC 290; the globular cluster NGC 362; the emission nebula NGC 248; and the spiral galaxy NGC 406.