Photometric Analysis of Two Young Open Clusters: NGC 1545 and NGC 2099

Abstract

We carried out a photometric study on two young open clusters NGC 1545 and NGC 2099 in the near-infrared region by making use of JHK_s of the 2MASS catalog and the GAIA DR2 survey. In this study, we utilized a method that is able to distinguish cluster stars from background stars. Our calculated results indicate that for both cluster NGC 1545 and NGC 2099, the number of members are 3059 and 2932, respectively. We have computed the cluster center of the two clusters and found it to be estimated at ? = 04^h20^m59^s.87, ? = 50^o15?58??.46, ? = 05^h52^m17^s.8, ? = 32^o33?5??.58, respectively. The limiting radius for both clusters is about 3.5 ± 1.1 arcmin and 29.2 ± 1.3 arcmin, respectively. The Color Magnitude Diagram, in GAIA DR2 Bands, for NGC 1545, enabled us to estimate the reddening at RP band to be E (BP- RP) = 0.09 mag, and E (BP- RP) = 0.08 mag, for G band. For NGC 2099, the reddening at RP band is estimated to be E (BP- RP) = -0.08 mag, and for the G band, it’s estimated to be E (BP- RP) = -0.08 mag. While in the 2MASS Bands, the reddening at K_s band is estimated to be E (J- K_s) = 0.00205 mag, and at J band it’s estimated to be E (J- H) = 0.001 mag for NGC 1545. For NGC 2099, the reddening at K_s band is estimated to be E (J- K_s) = -0.09 mag, however, and E (J- H) = -0.09 mag at J band. We obtained the distance modulus at RP band to be (m - M)_RP = 9.6 mag and 10.6 mag, and (m - M)_G = 10.4 mag and 10.6 mag, for the G band, whereas the distance modulus at K_s band  (m - M)_Ks = 9.5 mag and 10.6 mag, and (m - M)_J = 9.5 mag and 10.6 mag, for the J band., for NGC 1545 and NGC 2099, respectively.

In contrast, the luminosity and mass functions of these two open clusters, NGC 1545 and NGC 2099, have been estimated to be 1997.85842 M_? (for GAIA DR2 Bands) and 1847.36496 M_? (for 2MASS Bands) and 3289.40412 M_? (for GAIA DR2 Bands) and 3317.5277 M_? (for 2MASS Bands), respectively, while the mass function slopes are  -2.69397 ± 0.24234 (for GAIA DR2 Bands) and -2.69142 ± 0.26602 (for 2MASS Bands) and -3.37104 ± 0.65729 (for GAIA DR2 Bands) or -3.55212 ± 0.28216 (for 2MASS Bands) for NGC 1545 and NGC 2099, respectively. Finally, the dynamical state of these two clusters shows that NGC 1545 and NGC 2099 are clusters that can be considered as dynamically relaxed.