Optical variability of the Large Magellanic Cloud supersoft source RX J0513.9 - 6951 from MACHO Project photometry

Using the exceptional monitoring capabilities of the MACHO project, we present here the optical history of the LMC supersoft source (SSS) RX J0513.9 - 6951, for a continuous 3-year period. Recurring low states, in which the optical brightness drops by up to a magnitude, are observed at quasi-regular intervals. This provides a crucial insight into the nature of the supersoft sources and, in particular, a chance to investigate the poorly …