We have talked about rotation periods and spots on our objects before in several posts (e.g. weeks 195, 221, 268, 271). Today we have a look at a (preliminary!!!) result plot for a very large sample of YSOs for which we have identified rotation periods and measured their spot properties and their evolution.

In the plot the rotation period is shown along the x-axis. The vertical dashed line separates fast and slow rotators. The y-axis shows how much ‘excess’ emission in the near/mid infrared the object has. This means that sources above the horizontal line do have a large amount of hot dust in the inner parts of the disk, sources below do not. But they might have gas in the inner disk and/or disk material further out.

Every point represents a young star. The colour code indicates if the periodic variability is dominated by cold (red) or warm/hot (blue) spots. The colour code hence represents the fraction of time the object is found to have warm/hot spots. The size of the symbols shows in how many six months long parts of the light curve we were able to determine the spot properties reliably.

Now the fun part of the analysis starts. Trying to make sense and understand what these results mean and what they can tell us about the nature and evolution of these objects. What causes the warm spots? Does the presence of an inner disk influence the occurrence rate and/or properties of the spots? Does the rotation period, mass, or environment have any influence? AND: If they do (or not) we need to understand why! 🙂