RU Camelopardalis
RU Camelopardalis, or RU Cam, is a W Virginis variable (type II Cepheid) in the constellation of Camelopardalis. It is also a Carbon star, which is very unusual for a Cepheid variable. History RU Cam was reported as a new variable star in 1907. It was quickly recognised as one of the Cepheid class of variable stars. The first detailed study of the spectrum of RU Cam showed that it changed during the brightness variations. From partway down the descending branch of the light curve to just after minimum brightness, the spectrum is class R with hydrogen absorption lines. The spectrum then develops hydrogen emission lines. For several days either side of maximum brightness, the spectrum becomes a relatively normal class K. RU Cam remained a somewhat unusual W Virginis variable until 1964, when the relatively regular pulsation of about 1 magnitude almost entirely stopped. Since then the pulsations have varied from cycle to cycle, with amplitudes changing from several tenths of a magnitude to almost zero. The light curve has a more sinusoidal shape than when it was pulsating at full amplitude and the period changes erratically between 17.4 and 26.6 days. Properties RU Camelopardalis is both a Carbon