HAYDN (High-precision AsteroseismologY of DeNse stellar fields) is a proposed space telescope for asteroseismology in crowded fields. Globular clusters hold thousands of stars with nearly the same age and distance, which makes them clean tests of stellar physics. Their centres are so crowded that the pixels of Kepler, TESS and PLATO blend many stars together. HAYDN would combine much finer pixels with months of observation of a single field.
The concept comes from a white paper for ESA's Voyage 2050 long-term plan (Miglio et al. 2021), and the HAYDN consortium now presents it as a proposed ESA M-class mission. The white paper sketched a telescope of about 90 cm with a field of about one degree, pixels of about 0.25 arcseconds against 4 arcseconds for Kepler, and runs of 6 to 24 months on targets such as 47 Tucanae. By 2023, seismic masses had been measured in two globular clusters, for 75 red giants in M4 and 47 giants in M80 (Howell et al. 2022, 2023).
Where I come in
During my secondment at INAF-OAS Bologna, from September 2025 to March 2026, I wrote HAYDNsim, the simulation pipeline that forecasts the photometric noise of every star in the clusters on the mission's target list, so that the proposal's claims can be tested star by star. The pipeline and its stages are on the HAYDNsim page. I presented it on a poster at TASC10/KASC17 in Aarhus and in a talk at DFA Week 2026 in Porto.