A Comprehensive Study of Five Intermediate-age Pismis (2, 3, 7, 12, 15) Clusters Using Photometric and Astrometric Data from Gaia EDR3

Abstract

Open clusters are groups of stars that form simultaneously; hence, these are excellent probes to test theories of star formation, stellar evolution, and dynamics in the Milky Way disk. We carry out a detailed photometric and kinematic study of five poorly studied intermediate-age open clusters, Pismis 2 (Pi 2), Pismis 3 (Pi 3), Pismis 7 (Pi 7), Pismis 12 (Pi 12), and Pismis 15 (Pi 15), using the Gaia EDR3 database. By estimating the membership probabilities of stars, we recognized 635, 1488, 535, 368, and 494 most probable members for these clusters by using proper-motion and parallax data taken from Gaia EDR3. The radial density profiles of cluster members provide cluster radii of 4.′5–6.′5 for these clusters. Their ages range from 0.9 to 2.5 Gyr, and distances range, using parallax, from 2.15 to 5.10 kpc. The overall mass function slopes for main-sequence stars are found as 0.27 ± 0.16 (for 1.0–1.6 M ⊙ stars), 0.86 ± 0.27 (for 1.0–2.1 M ⊙ stars), 1.08 ± 0.32 (for 1.0–2.2 M ⊙ stars), 0.89 ± 0.38 (for 1.0–2.2 M ⊙ stars), and 1.07 ± 0.28 (for 1.0–2.1 M ⊙ stars) for clusters Pi 2, Pi 3, Pi 7, Pi 12, and Pi 15. Our obtained values of slopes are flatter in comparison with Salpeter’s value (x = 1.35) within uncertainty. The present study demonstrates that all these Pismis clusters are dynamically relaxed. We found that these objects follow a circular path around the Galactic center. We compute these clusters’ apex coordinates (A, D) and other kinematic parameters.