Data input into the database is continuing, and we have now 80100 images processed. There is still a backlog of just over 7000 images to work through, with new ones being submitted daily. The first volunteer helper has finished his training yesterday and a second one is going through training at the moment. Hence, we hope to reduce the backlog soon. If you know anyone else who would like to help, please ask them to get in touch.

This week we look at some of the new data of the variable star V505Ori, which is situated in the SigmaOri target region. In our recent paper “A survey for variable young stars with small telescopes: V – Analysis of TXOri, V505Ori, and V510Ori, the HST ULLYSES targets in the σ Ori cluster” we found that this source is an AA-Tau like object, with a period of 7.070d. These objects have an inner disk warp which periodically causes occultations of the star. In the data we analysed for this paper, the source had amplitudes of about 0.9mag in R and I, and 1.0mag in V. In the light curve shown above, one can see that the period has not changed, and it is still very much one week. However, the amplitudes are now much higher. In all filters they are of the order of 2mag, and even slightly higher in the V-band. In B, the source dims so much during the minima, that it is not detectable in the images we have.

So why has the amplitude changed? There must be more material now in the part of the inner disk (the warp) which periodically occults the line of sight to the central star. Thus, we are seeing more material moving closer to the star – note the 7d period indicates it is only about 15 solar radii from the star (assuming it is one solar mass). If that material will continue to move in closer and be accreted is not known. But with our long term  data we can in future track if there is a correlation and/or time lag between the amplitudes of the variations and the source brightness, to which the accretion rate contributes. Sounds like a nice student project 🙂