R Centauri – An Interesting and Perhaps Unique Mira Star

Presented by Stan Walker and Giorgio di Scala

The first recorded maximum of R Centauri was in 1871 but reasonable coverage dates from only 1891. It displays two clear maxima, which characteristic is shared by less than a dozen others of the thousand or so well studied Mira stars. We present observations of the changing light curve shape and amplitudes with supplementary UBV and BVRI measures which appear to differ dramatically from other Miras. The pulsation period is also changing, believed to be the result of a helium flash, the onset of this period change in 1922 being perhaps the only one observed.