This weeks light curve is of the star T Ori in the outskirts of the Orion Nebula M42. It is a known so called Herbig AeBe star at a Gaia distance of 403pc. Hence, it is a slightly more massive young star in this star forming region.

Of all the light curves shown so far over the last two years, this now has by far the most data points – almost 10,000. In the image above, we do show the B, V, and I-band data. The values are slightly shifted for better visibility. All frames have the same scaling of the magnitude axis and each one shows one of the eight available observing seasons for the object. Since almost the entire data for this field comes from a telescope in the Atacama Desert, we have very good time coverage, with data almost taken every day. There are of course longer gaps between the observing seasons, but other gaps (due to e.g. equipment failure) are few and far between.

In general the star varies by about one magnitude and never really breaks out of its magnitude range. Typically shorter term dipping events are very common, which at times appear semi-periodic. Around early 2015 and 2019 there are longer, and deeper dimming events visible, but they seem to be the exception for this object. We plan future more detailed analysis of objects like this, to study the distribution, properties and evolution of the material in the inner disk, which is most likely responsible for the observed variability.