ASTROPHYSICAL AND STRUCTURAL PARAMETERS, AND DYNAMICAL EVOLUTION OF THE OPEN CLUSTERS NGC 1245 AND NGC 2099

Authors : Hikmet ÇAKMAK, Orhan GÜNEŞ, Yüksel KARATAŞ

Pages : 525-538

Doi:10.18038/estubtda.673575

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Publication Date : 2020-12-28

Article Type : Research Paper

Abstract :We derive astrophysical and structural parameters of open clusters NGC 1245 and NGC 2099 from 2MASS JHKs and Gaia DR2 photometric / astrometric data bases. Their likely members have been determined from Gaia DR2 proper motion data. Our Einsert ignore into journalissuearticles values(B – V); values insert ignore into journalissuearticles values(2MASS); are slightly smaller than the literature values, whereas our Einsert ignore into journalissuearticles values(B – V); values insert ignore into journalissuearticles values(Gaia DR2); agree with the literature within the uncertainties. Their distance moduli/distances and ages are in good coincident with the literature. NGC 1245 has steep negative core mass function slope insert ignore into journalissuearticles values(MFs); insert ignore into journalissuearticles values(χ_core=-1.24);. It’s at halo insert ignore into journalissuearticles values(χ_halo=+0.78); and at overall insert ignore into journalissuearticles values(χ_overall=-0.95); MFs mean that it presents signs of small-scale mass segregation to the outer regions from its core, due to its [t_rlx insert ignore into journalissuearticles values(overall);,τ_overall ]=[302 Myr,5]. The MFs of NGC 2099 is very negative steep insert ignore into journalissuearticles values(χ_core=-2.67); in the core, and quite positive steep insert ignore into journalissuearticles values(χ_halo=+1.41); in the halo. This kind of MF slope steeping from the core to the outskirts indicates that low-mass 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 insert ignore into journalissuearticles values(χ_overall=+0.91); and its τ_overall=8 presents a sign of mass segregation. These OCs with the relatively large masses 8700 Msolar insert ignore into journalissuearticles values(NGC 1245); and 5660 Msolar insert ignore into journalissuearticles values(NGC 2099);, which locate at RGC > 9 kpc, expose to external perturbations such as tidal effects and shock waves, and they lose their stars in low-proportions.
Keywords : Galaxy open clusters and associations, open cluster NGC 1245, Individual Galaxy Stellar Content,