Tucana

Tucana


Transit Date of principal star:
26 August


The toucan is a brightly coloured bird of Central and South America, known for its over-large beak. Talkative and friendly, it makes a nice pet. Just feed it fruit and insects, along with the occasional lizard, and it will love you for life.

In the skies the Toucan is one of three exotic birds which are grouped around the South Pole. The other two are Pavo (the Peacock) and Apus (Bird of Paradise).

All three were introduced by Johann Bayer, an amateur astronomer from Augsburg, Germany.

Bayer's book Uranometria, published in 1603, had an enormous effect on astronomy, for a number of reasons. First, it was the first book to treat the entire skies; all star atlases thus far had only looked at the northern hemisphere and patches of the southern. In order to cover the entire southern hemisphere Bayer had to fill in some of the blanks. So he adopted a number of constellations that others had invented, and put them in his book. In all, he introduced a dozen new constellations.

With the labelling of a constellation's stars with the Greek alphabet, hundreds more stars were instantly named. Unfortunately many southern hemisphere constellations haven't received Bayer letters, and instead go under a very awkward naming system. But by and large, Bayer's system of labelling stars has been very convenient indeed.


The Toucan is one of the circumpolar southern constellations. If you live north of Mexico City or Bombay you won't find it. It has few Bayer stars, mostly at the four to five-magnitude range.

The constellation is famous for two deep sky objects: the large globular cluster known as 47 Tucanae (NGC 104), and the Small Magellanic Cloud, an unusual naked-eye galaxy (NGC 292).

The important stars in Tucana are few in number. Alpha Tucanae is an orange giant 130 light years away. Several other stars are of interest as binary systems (see below).


Double stars in Tucana:

Beta1 and beta2 Tucanae form a splendid binary, part of a multiple system: 4.3, 4.5; PA 168, 27.1".

Delta Tucanae has a faint companion: 4.5, 8.7; PA 279, 7.1".

Kappa Tucanae: 5.0, 7.7; PA 315, 4.8".

Lambda1 Tucanae: 6.7, 8.2; PA 82, 20.4".


Variable stars in Tucana:

Tucana has a delta-Scuti type variable and a pulsating variable (Lb), neither one of which is of much interest to the amateur observer.

Theta Tucanae is a delta Scuti type variable with a range of 6.06 to 6.15, and period of one hour 11 minutes.
Nu Tucanae is a pulsating variable (Lb): 4.75-4.93 with uncertain period.

Deep Sky Objects in Tucana:

Tucana is the home of the Small Magellanic Cloud and 47 Tucanae, both of which are worthy of Messier.

47 Tucanae (NGC 104) is a splendid globular cluster, bright and large, a naked eye object which ranks alongside Omega Centauri. The cluster is about 20,000 light years away.

It is found 4 SW of lambda Tucanae.
The Small Magellanic Cloud (NGC 292) is an irregular galaxy, a cloud-like object perhaps 200,000 light years away.

The Small Magellanic Cloud is a companion to the Large Magellanic Cloud, in Dorado.

These Magellanic Clouds are actually neighbours of our own Milky Way Galaxy.They are so named because they were first noted by Ferdinand Magellan in 1519.

The term "irregular galaxy" refers to the fact that no apparent shape can be seen, and that a great amount of interstellar matter is visible. The cloud contains a large number of variable stars; well over a thousand have now been catalogued.

NGC 362 is another globular cluster, at the edge of the SMC but much closer (about 40,000 light years away). This cluster is nicely seen in binoculars.


For a little more on Tucana visit the Binocular Section.


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