The brightest star of Chamaeleon is of but magnitude 4.07, and is single.
Properties
Alpha Chamaeleontis is fairly close, at an accurately-known distance of 63.5 light years. It radiates 7.1 solar luminosities, which yields a radius 2.3 times the Sun's. Rotating with a minimum equatorial velocity of 29 km/sec, the star makes a full turn in less than 2.3 days. Only these limits are known, since the axial tilt is undetermined.
α Cha's spectrum shows that it is a relatively rare, white giant of spectral class F5 III, with an uncertain surface temperature of 6770 K. However, its temperature and luminosity seem to indicate that the star is not actually a giant, but an advanced hydrogen-fusing main-sequence star of 1.55 solar masses. That is its one anomaly: its spectrum shows it to be a older giant with a dead helium core, yet its luminosity and temperature imply that it is a younger dwarf.
Evolution
At an age of about 1.5 billion years, α Cha is nearing the end of its main-sequence lifespan. As might befit such a star, it has an outer corona that radiates strong X-rays, heated to 3.7 million K through magnetic action caused by rotation and convection (as in the Sun).
As stars age, the chemical compositions of their surfaces can change. True giants dredge up nitrogen newly formed from internal nuclear reactions, leading to a high ratio of nitrogen to carbon. Lithium, on the other hand, becomes depleted, since it is cycled downward by convection to hot interior regions where it is easily destroyed by other nuclear reactions. Such stars should have both low lithium and high nitrogen. However, in α Cha, the abundances of both are curiously high, for reasons not understood. The star thereby looks old and young at the same time.
[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]