The age and metallicity dependence of the near-infrared absolute magnitude and colour of red clump stars

Understanding the age and metallicity dependence of the absolute magnitude and colour of red clump (RC) stars is crucial for validating the accuracy of stellar evolution models and enhancing their reliability as a standard candle. However, this dependence has previously been investigated in the near-infrared across multiple bands only for -1.05 ≤ [Fe/H] ≤ 0.40, a range accessible through the star clusters in the Large Magellanic Cloud. Therefore, we used star clusters in the Small Magellanic Cloud and the Milky Way Galaxy to investigate the age and metallicity dependence of the absolute magnitude and colour of RC stars in the near-infrared for a broader parameter space (0.45 ≤ Age (Gyr) ≤ 10.5, -1.65 ≤ [Fe/H] ≤ 0.32). Comparison of our results with three isochronous models BaSTI, PARSEC, and MIST reveals that the age dependence of the absolute magnitude for young RC stars aligns well with theoretical predictions, within the fitting errors of the multiple regression analysis. Additionally, the observed colour shows good agreement with the theoretical models. Notably, the J − KS colour, which spans a wide parameter space, reproduces the distribution expected from the theoretical model.