We conclude that eMSTO in SAI 45 is mainly caused by the different rotation rates of stars as the SYCLIST synthetic population with different rotation rates was able to reproduce the observed eMSTO, and stars in the red part of the eMSTO were preferentially concentrated in the inner region, which again hints at different rotations being the reason for the extension in the upper MS. This indicates that eMSTO is a stellar evolution rather than star formation phenomenon in SAI 45. The apparent age spread is found to be similar to the apparent age spread predicted on the basis of the age spread and cluster age relation predicted by rotation models. The color-magnitude diagram of SAI 45 hosts an extended main-sequence turnoff (eMSTO). The logarithmic age of the clusters are determined to be 8.82 ± 0.10 and 9.07 ± 0.10 yr for SAI 44 and SAI 45, respectively.
The average distances to SAI 44 and SAI 45 are calculated to be 3670 ± 1 ± 47 pc. The stellar memberships are determined using a statistical method based on Gaia eDR3 kinematic data, and we found 204 members in SAI 44 while only 74 members are identified in SAI 45. We carry out a detailed photometric and kinematic study of the poorly studied sparse open clusters SAI 44 and SAI 45 using ground-based BVR cI c data supplemented by archival data from Gaia eDR3 and Pan-STARRS.
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