X-ray lightcurve of V1647 Ori
Observations of the young, low-mass star, V1647 Ori, with the XMM-Newton, Chandra and Suzaku observatories, have revealed periodic variations in the X-ray emission from this protostar.
The authors propose that these periodic changes arise from localised 'hot spot' regions of X-ray plasma that are moving in and out of our line of sight as the star rotates. Rises and falls in the light curves would then correspond to appearances and disappearances of X-ray bright spots.
This lightcurve shows the best-fit result of their model to data from XMM-Newton and Suzaku. The green line indicates the contribution from the bright spot, the blue line the contribution from the blue spot, and the red line is the modelled total emission.
The sequence above the lightcurve depicts the locations of hot spots at the corresponding phases.