What a difference four months can make. This week we look at the light curve of V505Ori. We identified this object as a periodic variable in our recent paper. It has a period of 7d 1h 41m, with sharp-ish minima and broad maxima. Our analysis attempted to model the variation with surface spots, but it turned out that this was not possible. Most likely this source is hence an object with a warped inner disk, with material orbiting around the star and periodically dimming the light from the object.
In the plots we show a part of the light curve from April last year. This shows the behaviour discussed in the paper, and covers the last month of data before the object moved too close to the Sun for observations. The periodicity is clearly detectable, but there is also an underlying trend in the brightness, the peaks are getting higher, while the sharp minima also vary in brightness. This can have all sorts of reasons, such as longer term changes in the accretion rate, material further out in the disk changing the line of sight extinction slowly, or material in the disk warp moving.
The second plot shows the same duration data for August this year, just after the source has become observable again. But now the object looks quite different. While here is still some (almost) periodic behaviour, the period seems to be slightly longer. Thus, there could have been a shift in the orbital radius of the inner disk warp. In other words, most of the material in the warp that occults the star is now further away from the star. Thus, the period is longer. Also, there is a very sudden and deep (1.4mag) drop in brightness for three observing days around JD=2459815. The shape of the underlying light curve still seems to continue. Thus, there might be some other dense clump of material, further out in the disk, which has occulted the star in addition to the disk warp for 3-4 days. It might be worth checking through the entire light curve to see if this is a one-off event, or a regular occurrence. If anyone want’s to look at this, use the light curve plot feature on the website and let us know what you find. Thanks!