This week we are revisiting an old friend of this feature, the young star GM Cep. The last time we looked at it was in June 2025, week 335. The object is a slightly more massive object that shows frequent dimming events on all sorts of timescales with amplitudes of up to one magnitude.
In the above plot we show the V and I-band data for the star from the last year of observations. And indeed all the usual features are represented. A roughly 200day long dimming event is apparent, which is the second such event in as many years. On top of this there are short term events that range from a few weeks to days.
At some point we will investigate these short events in all light curves more closely. At first sight they look randomly distributed in time. However, it might be that a small subset of these short term events occurs periodically. These would then represent good candidates for gravitationally bound structures crossing the central star during their orbit – i.e candidate protoplanets. The problem is not so much to find the events, it is to work out which ones are potentially the periodic ones, as they might make up only a very small fraction of all the dimming events in a given light curve. And some of the periodic ones might fall into observational gaps …