This week we remain in the V555Ori target field region, and have a look at the light curve of the young star TT-Ori. In the plot above we show the V, R, and I-band data. For the brighter stages of the object, the database also contains B-band measurements. Of course, for now, only the last few months of data are accessible, until we fully restore the database – more progress updates on this soon.

The source has been flagged up as the Gaia alert Gaia22ehy in October 2022, and it has declined in brightness since. In total it has dimmed by about 2.5mag from the peak. Our data only shows the last, slow decline of on average one magnitude over the last 5months. The initial 1.0-1.5mag dimming occurred over a period of just 3 weeks.

We can see that this object varies typically, like many other young stars, by about one magnitude on short timescales, compared to its long term average. And the longer term trends (over several months) are variations of the same order of magnitude. These long and short term trends are usually a combination of accretion rate and extinction changes. We will have a summer student, hopefully starting next week, that will (amongst some other things) look into finding a way to identify light curves (or parts of light curves) that can be attributed to just one of these causes for variability. This is important as we can then study the statistics of the variation for the two main causes separately. This will enable us to infer insights into the inner disk structure and the accretion flows onto the star.