This week we look at the young star TX Ori. It is situated in the Sigma-Ori cluster, which is basically situated just to the south of the eastern belt star (Alnitak) and half a degree west of the horsehead nebula. We had a look at the long term light curve of the object last year, prior to starting our campaign on the field to investigate it in more detail. In the figure above we show the HOYS data for the star during last winter. For best visibility only I, V, and B are shown. We also have the same amount of data in R and the occasional U and Halpha data.
As you can see, the star constantly varies in all filters and time scales. It changes it’s brightness by up to two magnitudes in V. We are currently working on an analysis paper to investigate the nature of the source. The changes in brightness and colour seem to indicate that most of he variations are caused by variable extinction. Hence, we ‘see’ the star almost edge on and material in the disk moves in and out of the direct line of sight to the star.
However, the changes in colour do not match exactly what is predicted for dust dimming the light. This most likely indicates that the scattering properties of the dust grains are unusual (they have grown in size and might have ices on their outside) and that a sizeable fraction of the light we receive from the star is scattered light of the surface of the disk and not directly from the star. More on this in the paper…..coming soon…..