Two weeks ago we looked at the new Gaia alert source Gaia24avc, which was situated in the Elephant Trunk Nebula region. On the same date the alert source Gaia24avb was also published, and is situated in the same target field. The light curve for this source over the last year is shown in the above image.

The star is a known young stellar object and, similar to Gaia24avc, has been flagged up due to a dimming event. Both our HOYS and the Gaia data show that this object has a more well defined baseline brightness which does not change too much over time. In other words, the light curve is mostly flat and un-interesting. However, there are a number of short dimming events which only last a day or two. Thus, only some of them, more likely the slightly longer ones do get picked up by Gaia. There are only about 15 of these in the almost 10 years of Gaia data. But we can identify about the same number in just one year of HOYS data, which has a much higher cadence.

This shows why the design of HOYS as high cadence and long term survey is important. We can much better characterise the short term fluctuations, but also identify how things change in the long term. For example, these short term dimming events are usually caused by small, fast moving clumps of material in the inner disk. We can study if their numbers (the number of dips in the light curve) changes over time. And if there are more or less of these dimming events, we can see if this at the same time has a longer term influence on the baseline brightness. We can basically ‘watch’ how the number of small dense clumps in the inner disk changes over time….another interesting student project coming up 🙂

Happy Easter Everyone!