Haywards Heath College students, in partnership with Orbyts Fellow Jake Hanlon from Mullard Space Science Laboratory, embarked on a research project to search for transiting exocomets orbiting the young dwarf star AU Microscopii (AU Mic). The study and detection of exocomets, which are comets orbiting stars outside our solar system and are composed of ice, dust, and rocky material, is a new and exciting field that helps our understanding of planet formation and provides fundamental answers about our own solar system. When exocomets approach their host star, rising temperatures cause their ices to sublimate, releasing gas and dust that may form tails.

AU Mic, a young dwarf star approximately 22 million years old and located about 10 parsecs (~32.62 light-years) from Earth, is an ideal target for exocomet detection due to its age and active debris disk. Its luminosity is about 10.2% of the Sun's, and it is known to have a planetary system with two confirmed warm Neptunes and two other planetary candidates. These characteristics are similar to Beta Pictoris, the first system where exocomets were detected. The Transiting Exoplanet Survey Satellite (TESS) collects data on young stars, which was analysed in this project to find transiting exocomets around AU Mic. The transit method involves analysing light curves for specific patterns produced by transiting exocomets, specifically a unique "upside-down dorsal fin" looking dip in the star's light curve.

The project successfully identified dorsal fin shapes in the TESS light curve of AU Mic. However, the highly active and young nature of AU Mic introduces significant noise into the data, making it difficult to definitively confirm exocomet detections. One particular dip initially appeared to be a characteristic exocomet "dorsal fin" but was identified as a transit of one of AU Mic's planets, with the dorsal fin shape resulting from a stellar flare increasing the star's brightness simultaneously with the planet blocking some of its light. If a detected "dorsal fin" were a transiting exocomet, its short transit time would suggest it is very close to AU Mic and likely on a collision course with the star. AU Mic is scheduled for further observations by TESS this summer, and future work will involve analysing this new data for more convincing exocomet transits!