Photometric and Astrometric investigation of the two open star clusters Stock 3 and Stock 18 using the PPMXL Catalogue

Our study aims to make astrometric and photometric analyses for the two open star clusters; Stock 3 and Stock 18. By using PPMXL catalogue and proper motion data, which considered as the initial key step towards determining all the astrophysical parameters, the membership of both clusters became achievable. we got 419 and 86 probable members for Stock 3 and Stock 18 with probabilities greater than 50%, respectively. Followed by the constriction of the color-magnitude diagrams and depending on the visual fitting isochrones, their ages and distances were derived as 16 Myr, 2879.9±586.0 pc (for Stock 3) and 4 Myr, 2987.8±609.0 pc (for Stock 18), respectively. Using the high probability group, the mean proper motions of the probable members of Stock 3 are -0.6627 ± 0.3013 and -0.9701± 0.2704 mas yr−1 in right ascension and declination, respectively. While those of Stock 18 are -4.6063 ± 0.6429 and -3.850 ± 0.659 mas yr−1, respectively. The effectiveness of the membership selection is equal to 0.192 and 0.178 for Stock 3 and Stock 18, respectively.