The Constellation Tucana the Toucan
Home to the Small Magellanic Cloud and a Brilliant Globular Cluster
Jan 20, 2009
The constellation of Tucana the Toucan lies deep in southern skies. It is visible year round from the Southern Hemisphere because of its location so close to the South Celestial Pole. It lies between Octans, the constellation that contains the South Celestial Pole, and Grus and Phoenix, which lie on the opposite side.
The Stars of the Constellation Tucana
The stars of Tucana are not particularly bright or remarkable, making this constellation harder to pick out compared to its globular cluster and galaxy that anchor the southern edge. The brightest star in Tucana is Alpha Tucanae, a magnitude 2.87 star that lies 198.6 light-years from Earth. On the opposite side of the constellation from Alpha is Beta Tucanae, a star system containing six stars loosely bound together. Beta 1 is the brightest and shines at magnitude 4.36, and Beta 2 shines at magnitude 4.53, and Beta 3 shines at 5.07. The whole system is an average of 140 light-years from Earth.
Deep-Sky Objects in Tucana
The main attraction in the constellation of Tucana the Toucan is its beautiful globular cluster, 47 Tucanae, and the Small Magellanic Cloud, a satellite galaxy of the Milky Way. 47 Tucanae is sometimes referred to as NGC 104. It shines bright at magnitude 4.0 and is easily visible with the unaided eye. Use binoculars or a telescope to resolve the stars of the cluster. 47 Tucanae lies 16,700 light-years away and is part of the Milky Way Galaxy. But just over two degrees away visually is another galaxy that lies 200,000 light-years away. Despite its great distance, the Small Magellanic Cloud (SMC) is one of the closest galaxies to Earth. It is visible to the naked eye as a misty, cloudy patch in the sky on dark nights. The SMC is an irregular galaxy but has a central bar as part of its structure, looking like a disturbed former spiral.
The SMC has a number of clusters and nebulae visible within its expanse. An excellent target for a telescope, clusters of 9th, 10th, 11th, and 12th magnitude stream through its length and out one tail. The Small Magellanic Cloud has a nearby kin, the Large Magellanic Cloud, found in the constellations Mensa and Dorado. Both of these nearby galaxies are being sucked inward by the Milky Way Galaxy and will eventually be absorbed by it.
On the opposite edge of the SMC's curving shape from Tucana is NGC 362, another bright globular cluster. NGC 362 is a bit dimmer than 47 Tucanae, at magnitude 6.6, but still is a good target in binoculars or small binoculars.
Tucana is a Southern Hemisphere constellation that holds many deep-sky observing targets that are worth exploring.
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