Similar to last week we have a look back at an object that has featured before. This week it is the variable star V350Cep. The star is situated just north of the cluster NGC7129. Gaia places it at a distance of more or less exactly 900pc, very similar to the cluster itself.
In the figure we show the current light curve in R and I. For better visibility we shifted the R magnitudes by one mag. As one can see, the star showed a deep eclipse event lasting about two months at the very beginning of the HOYS observations. Indeed this was the first ever Gaia alert that happened in one of our target fields. Thus, the object is now also known as Gaia16alt.
Compared to last weeks object, this one seems to be rather boring. After the deep eclipse, the object slowly increased its brightness for the next year. Since then it has very slowly faded at a rate of about 0.1mag per year. In the last year the fading has stopped and even a small rise of 1-2percent in brightness can be seen. No other deep occultations are seen in our, or the Gaia data (which starts a bit earlier). This hints that the occulting structure that caused the eclipse was situated further out in the disk, or maybe was an object along the line of sight, not actually associated with the star itself.
On top of the long term changes, the source is also varying at the 10percent level on very short timescales. These variations, seen as scatter of the data points, are real, as they occur in all filters in the same way. This hints to either short term accretion rate changes or small scale structures in the inner disk changing the extinction towards the source. A detailed analysis of the colour changes in those short term variations is needed to understand their cause.