Chamaeleon (“the chameleon”) is a small, dim southern constellation that like its namesake is difficult to find. It was devised by astronomer Petrus Plancius based upon the observations of Dutch navigators, with its brightest star, Alpha Chamaeleontis, a blue-white giant found 63.5 light years from Earth with a visual magnitude of +4.06.
Chamaeleon is the 79th largest of the 88 recognized constellations, taking up an area of just 132 square degrees of the southern sky. It can be viewed all year round by observers located between 0° and -90° of latitude, although best seen in April. Chamaeleon lies close to the south celestial pole to the south of Crux, with its bordering constellations including Apus, Carina, Mensa, Musca, Octans, and Volans.
Bayer Constellation Family
Chamaeleon is a member of the Bayer Family of constellations, together with Hydrus, Dorado, Volans, Apus, Pavo, Grus, Phoenix, Tucana, and Indus.
In the late 16th century, Dutch explorers Pieter Dirkszoon Keyser and Frederick de Houtman studied the stars of the southern sky on their way to the East Indies (Southeast Asia), with their observations later used by Petrus Plancius in 1597 to devise 12 new southern sky constellations. All but one, were named after exotic animals, including Chamaeleon.
– Alpha Chamaeleontis, the constellation’s brightest star, is a blue-white giant (F5III) situated 63.5 light years from our solar system that shines with a visual magnitude of 4.06. This 1.8 billion years old star is 2.3 times bigger than the Sun, with 1.4 times its mass, and 7.64 times its luminosity. Alpha Chamaeleontis has an equatorial
rotational velocity of about 29 km/s, producing a full turn every 2.3 days.
– Gamma Chamaeleontis, the second brightest star in Chamaeleon, is a red giant (K5 III) located 418 light years away of magnitude 4.12. It has 67 times the Sun’s radius, and 864 times its luminosity.
– Beta Chamaeleontis, the constellation’s third brightest star, is a blue dwarf (B5Vn) found 270 light years distant whose visual magnitude ranges between 4.24 to 4.30. This 22.7 million year old star is 2.40 times larger than the Sun, with 5 times its mass, and a rotational velocity of 255 km/s.
Other stars of interest in Chamaeleon includes the Mira-type variable star R Chamaeleontis, whose magnitude ranges between 7.5 to 14 over a 334 day period; the T Tauri variable star CT Chamaeleontis with a magnitude variation between 12.31 and 12.43; the binary star Epsilon Chamaeleontis; the orange giant Delta-1 Chamaeleontis; and the blue subgiant Delta-2 Chamaeleontis.
Notable Deep-Sky Objects
– Eta Chamaeleontis Cluster (Mamajek 1) is an open star cluster found 316 light years away. This eight million years old cluster consists of 13 young stars, with 3 stars dominating its view through a small telescope, the brightest of which is the 5.5 magnitude Eta Chamaeleontis.
– Chamaeleon Cloud Complex is a vast star forming region that covers most of the Chamaeleon constellation, as well as parts of neighboring Apus, Musca, and Carina. It is located around 600 light years away, and contains the dark molecular clouds of Chamaeleon I, Chamaeleon II, and Chamaeleon III, which are forming T Tauri type stars, the most prominent of which are in the Chamaeleon I cloud.
– NGC 3195 is a planetary nebula located 5,500 light years from Earth with an apparent magnitude of 11.6. It is the southernmost of all big, bright planetary nebulae, and through a 10-inch telescope looks like a white, dumbbell shaped fuzzy patch.
Other objects of interest in Chamaeleon includes the spiral galaxies NGC 3149 and NGC3620; and the globular cluster ESO 37-01.