This week we have look at the light curve of the young star Mayrit 789281. It is located in the sigma-Ori target region of HOYS. This field has very good coverage in the last 5yr.
We show the long term V, R, and I-band photometry in the first plot. One can see that the star is reasonable bright and it is listed as having a spectral type G2.5. Thus, it is very similar to the sun, and probably only slightly more massive. We can see that on timescales of years, the star varies by about 0.1mag (or 10%). The scatter at a given time is almost of the same order of magnitude, and looks like noise at this zoom level. However, it is caused by short term variability.
This is shown in the second image. This is a zoom into the 2022-2023 observing season – the 3rd ‘block’ of data points from the right in the long term light curve. One can see that it stars for about 2-3 months with an almost periodic variability (it is not periodic :-)) which then disappears. The variations on a week long timescale can be of the order of 0.08mag (8%). The day to day variation is usually below a few percent.
In other parts of the data one can see similar behaviour, with the almost periodic variations being extremely rare. Thus, this part was probably caused by material in the very inner disk that occulted the star semi periodically during its orbit, before the structure disappeared. A detailed investigation of the colour changes during the time can shed some light on this and reveal if this variability is consistent with orbiting dust in the inner disk. …. more to do for a keen student 🙂