2025PASJ...77..773G

High-energy gamma-rays have been detected in the region of LHAASO J2108+5157 by the Fermi-LAT, HAWC and LHAASO-KM2A observatories. Cygnus OB2 in Cygnus-X has been confirmed as the first strong stellar cluster PeVatron in our Galaxy. Thus, the star-forming regions Kronberger 80 and Kronberger 82, located in the field of LHAASO J2108+5157, are analyzed to evaluate their stellar population and potential as associated PeVatron candidates. A distance of 10 kpc is adopted for Kronberger 80, while $\sim$1.6 kpc is estimated for Kronberger 82. Based on stellar densities, we report that their cluster radii are ${2{^{\prime }_{.}}5}$ and ${2{^{\prime }_{.}}0}$, while infrared photometry reveals poor stellar content in massive O-type stars in both cases. From optical data, the estimations of cluster ages are 5-12.6 and $\lesssim$5 Myr, respectively. We conclude that, in contrast to the stellar content of Cygnus OB2, it is unlikely that Kronberger 80 and Kronberger 82 are PeVatrons associated with LHAASO J2108+5157. The presence of a PeVatron in this region remains a mystery, but we confirm that the two Kronberger regions are star-forming regions undergoing formation rather than evolution.