The HOYS winter target that is visible the longest each spring is NGC2264 (The Christmas Tree Cluster). Within it there is a large variety of young and variable stars. Amongst them is the known T Tauri star ESO-HA 464, which is one of the fainter objects in our data with an I-Band magnitude of about 16mag.
Based on the first five years of our HOYS data the star isn’t doing anything unusual. It varies by about half a magnitude around its average in a more or less random pattern. The typical T Tauri star behaviour. About a week ago, the object was flagged as as Gaia21bsq, because it appeared fainter by about one magnitude in the latest Gaia observation, compared to earlier data.
A more detailed look at the light curve shows that, starting about one year ago, the object is undergoing a long term dimming event, about one magnitude deep. Such events are rare, but HOYS has found a few already. For example 2MASS J20505039+4450115 which was published before as light curve of the week. These events are either caused by disk structures further out in the disk, or by material being moved into the inner disk. Based on the spectral energy distribution, which shows a large amount of excess emission at mid and far infrared wavelengths, the object is clearly surrounded by a massive accretion disk.
HOYS is ideally set-up to find, follow-up and investigate these rare, long-term events, as we are monitoring hundreds of stars over a long time. We will keep imaging this one for the next week or two before it gets too close to the Sun and we will see what the star does when it becomes visible again at the end of the summer.