This week we look back at an old friend of the project – V350Cep. It has been 16 months since it last featured as light curve of the week. This source was the first Gaia altert object (Gaia16alt) we found in the HOYS fields, and which we did see change before the alert came out. It is situated in the NGC7129 star forming region in Cepheus. The original alert flagged the object up because it had a ~2mag dip in brightness lasting for 2-3months, back in 2016. In the 5.5yrs since, it has shown long term changes on >1yr timescales, as well as short term, day to day variations.
The long term changes are probably due to changing extinction along the line of sight in the outer disk. This is supported by the fact that the total amplitude in V is about 0.6mag and in the I-Band only 0.2-0.3mag. The short term variations have typical amplitudes of 0.1mag (I) to 0.2mag (V) hence probably also caused by dust, but in the inner disk, causing shorter duration variations. We have looked to see if there are any indications of periodicity in these fluctuations, but no real periodicity is apparent in the periodograms.
In the plot we show the V, R, I and Halpha photometry. Note that V and I are shifted for better visibility. One can nicely see that the object is a strong Halpha emitter, with the R-Halpha colour consistently of the order of 0.5mag. Thus, indicating strong accretion processes.