Apus, the Bird of Paradise, is a southern, circumpolar constellation lying between the southern celestial pole constellation of Octans and the prominent triangle of stars that make up the Southern Triangle of the Triangulum Australe constellation. Apus is faint and does not present any readily identifiable shape, although three of its brighter stars can be seen as a small triangle.

History

In the late 16th Century the Dutch East India Company were exploring the far southern hemisphere latitudes for trading opportunities. During the 1595 expedition Pieter Keyser and Friedrich Houtmann recorded the positions of 196 stars near the south celestial pole that had previously been unseen by northern based astronomers. These stars were later formed into twelve new constellations and were adopted by astronomer Johann Bayer in his star atlas of 1603 Uranometria to fill in unnamed areas of the southern sky. Bayer attributed the name Apus Indica, or Bird of India to tales by early Dutch seafarers, who had recorded that gifts of live birds were made to European travellers.

It is the Bird of Paradise that is depicted in Uranometria, but another interpretation originates from the Greek word 'apous' meaning, without feet. This refers to the European Swift, which was reputed not to have any legs as it was always seen to be in flight and never alighting.

Principal Stars

Because of its far South position in the sky, near to the southern celestial pole, the stars of Apus were not seen by the ancient astronomers. Consequently none of its stars were given proper names and therefore are known only by their attributed Greek letter classification.

None of the stars in Apus are brighter than Alpha Aps which is an orange giant at +3.81 magnitude. Delta Aps is a widely spaced double star. Both components are orange giants and can be readily seen with binoculars. The primary of the pair is an irregular variable between +4.7 and +4.9 magnitude, with an orange colour biased towards red. The secondary is 5.3 magnitude¹ and is orange in colour.

Kappa Aps is another double, although slightly fainter with
magnitudes of +5.37 and +5.62. Theta Aps is a variable star of +6.4 magnitude, dimming to +8.6 every 119 days.

Clusters

NGC6101 is a faint globular star cluster of about ninth magnitude and lies north of Gamma Aps.

Another Bird of Paradise

Although the constellation Apus is named from the avian Bird of Paradise, there is also a remarkable flower that has been named from it. The Strelitzia shares the name due to its beautiful Crimson/orange/yellow flower that resembles the plumage of the bird. It is very difficult to grow outside its home environment of South Africa.