R Centauri

During the June Johannesburg Centre meeting, Brian Fraser demonstrated this variable at the eyepiece. My observations of it go back to the 1950's. It happens to be a very interesting long period variable and Burnham devotes more than a page to it:

"A long period variable star, discovered by Gould in 1871. At times it has reached naked eye visibility, reaching magnitude 5.3. In the Harvard Second Catalogue of Variable Stars its period is given as 568.2 days but now appears to be about 547 days... A changing period seems to imply a rapid change in the star's internal structure but very little else can be said until the mechanics of the pulsating stars is more thoroughly understood.

The period, in any case, is unusually long for stars of the Mira class. The really peculiar feature, however, is that the light curve shows double maxima and minima. The minima quite regularly alternate between mag 9 and 11, occasionally sinking to a deep minimum of mag 13. The maxima are nearly equal, but the slightly higher one systematically follows the shallower minimum. . ."

Readers of CANOPUS should bear in mind that Burnham's description is largely based on the observations by amateurs using little telescopes. Makes one think, doesn't it?

Danie Overbeek.
Tel 011 453 6918
danieo@global.co.za