RX-51940.1-1025 - A NEW ASYNCHRONOUS AM-HERCULIS SYSTEM

We present optical spectroscopy and white light photometry of RX J1940 . 1-1025 over a period of one year. From the photometry two periods ca n clearly be distinguished. The shorter one with 12116.3s is also the period of the radial velocities of the narrow emission line components and the period of narrow dips also seen in the X-ray data. This short er period is interpreted as the orbital period. The longer period of 1 2151s is also present in the X-ray data and is interpreted as the spin period of the white dwarf. We find a phase modulation of the X-ray li ghtcurve with the beat period of 49.5 days. Our measurement of circula r polarization of about 2% confirms the conjecture that RX J1940.1-102 5 is an AM Her system.