Student researchers from Brampton Manor Academy, in collaboration with Orbyts Fellows Alex Thompson and Rafael R. from UCL Physics and Astronomy, investigated the stellar variability of AU Mic, a young, cool exoplanet host star known for its activity. By using the Las Cumbres Observatory telescope network, students performed photometry, or the measurement of light, over a month to observe how the star's brightness changed over time. This research is crucial because understanding the activity of a host star is essential for accurately interpreting observations of its exoplanets, which can be contaminated by stellar features like starspots and flares.

To accurately measure the star's flux, the team utilised the photutils Python package to perform aperture photometry, isolating the light from AU Mic while correcting for background sky brightness. A crucial step involved using four non-variable comparison stars as a control to normalise the observations, which helped to correct for atmospheric and weather-related fluctuations. This process was applied to both a 2024 and a 2025 dataset, ensuring the integrity of the collected data.

The results of the analysis revealed that the team successfully detected stellar variability in AU Mic. However, the observed changes in brightness did not display a strong correlation with the star's rotation period, which was the initial expectation. This unexpected finding suggests that there are other complex processes at play, such as frequent stellar flare events, influencing the star's light output, and may also be dependent on the choice of models that the team used.

In conclusion, this research confirms that AU Mic exhibits variability, but the underlying mechanism for this variability is more complex than initially hypothesised. To fully understand the nature of this phenomenon, further work is needed to benchmark the methodology against other established methods. This would help to ensure that no errors were introduced and would provide a clearer picture of the processes driving the activity of this temperamental exoplanet host star!