Akademik Veri Yönetim Sistemi
Eskişehir Technical University Journal of Science and and Technology A- Applied Sciences and Engineering, cilt.21, sa.4, ss.525-538, 2020 (Hakemli Dergi)
We derive astrophysical and structural parameters of open clusters NGC 1245 and NGC 2099 from 2MASS JHKs and GaiaDR2 photometric / astrometric data bases. Their likely members have been determined from Gaia DR2 proper motion data.Our E(B – V) values (2MASS) are slightly smaller than the literature values, whereas our E(B – V) values (Gaia DR2) agreewith the literature within the uncertainties. Their distance moduli/distances and ages are in a good agreement with the earlystudies. NGC 1245 has steep negative core mass function slope (MFs) (𝜒𝑐𝑜𝑟𝑒 = −1.24). Its halo (𝜒ℎ𝑎𝑙𝑜 = +0.78) and overall(𝜒𝑜𝑣𝑒𝑟𝑎𝑙𝑙 = −0.95) MFs indicate small-scale mass segregation from its core to the outer regions, due to its[𝑡𝑟𝑙𝑥(𝑜𝑣𝑒𝑟𝑎𝑙𝑙), 𝜏𝑜𝑣𝑒𝑟𝑎𝑙𝑙] = [302 𝑀𝑦𝑟, 5]. The MFs of NGC 2099 is very negative steep (𝜒𝑐𝑜𝑟𝑒 = −2.67) in the core, and quitepositive steep (𝜒ℎ𝑎𝑙𝑜 = +1.41) in the halo. This kind of MF slope steeping from the core to the outskirts indicates that lowmass stars in the core are transferred to the cluster's outskirts, while massive stars sink in the core, because of mass segregation.NGC 2099's flat overall MFs (𝜒𝑜𝑣𝑒𝑟𝑎𝑙𝑙 = +0.91) and its 𝜏𝑜𝑣𝑒𝑟𝑎𝑙𝑙 = 8 indicate mass segregation. These OCs with the relativelylarge masses 8700 M (NGC 1245) and 5660 M (NGC 2099), which locate at RGC > 9 kpc, expose to external perturbationssuch as tidal effects and shock waves, and they lose their stars in low-proportions.