Winter is coming. We have now uploaded and processed the data from August for many of the Orion Targets. Hence we get our first look at how the objects are behaving after their annual pause of visibility due to the Sun being in the way. Above we show the light curve of an old friend of the project and this feature: TXOri.

This star is an Orion variable in the sigma-Ori target field. This means it is a young star which shows stochastic variability. And indeed this is what we have seen from this source when we looked at it before, e.g. here, more or less a year ago. In the short part of the light curve shown above, we see that currently the behaviour almost looks periodic (but not quite), with almost one magnitude changes over the course of roughly one week.

While this timescale roughly is consistent with typical rotation periods for these kind of stars, one needs to be cautious with this interpretation. It is possible that orbiting disk material in the inner disk can create a similar pattern causing regular occultations. Or the pattern could simply be a coincidence. For irregularly varying stars like this one, one needs to investigate a large number of such short parts of their light curve to see if several of them show the same period. This can allow us to identify the rotation period of the star despite its usually stochastic behaviour. One research project we are planning is to do exactly this. Cut the the light curves of stars into many small pieces, determine how periodic the light curve is in each piece and also if it is bursting/dipping or symmetric and look at the evolution over time of the behaviour.