Photometric analysis of newly discovered open clusters SAI 24 and SAI 94 based on PPMXL catalogue

Abstract

In our present work, we studied the photometric characteristics (core radius, limiting radius, reddening... etc.) as well as their dynamical state of the two newly discovered open clusters, SAI 24 and SAI 94. We investigated their photometric properties in the J, H, and Ks bands with the PPMXL catalogue. A method of separating open cluster stars from those belonging to the stellar background has been employed. The results of our calculations indicate that the numbers of probable members in SAI 24 and SAI 94 are 202 and 199, respectively. We have estimated the cluster center for SAI 24, i.e. α2000 = 02h 59m 26 .s36 and δ2000 = 60° 33' 02.''50 and for SAI 94 is α2000 = 08h 10m 16 .s36, δ2000 = −46° 17' 07.''91. The core radii rcore for SAI 24 and SAI 94 are found to be (1.92 ± 0.38) arcmin and (1.22 ± 0.10) arcmin, respectively and in the same manner the limiting radii rlim are about (2.45 ± 0.64) and (3.07 ± 0.57) arcmin. From the color-magnitude diagram, in view of the approximate logarithmic ages for SAI 24 and SAI 94 of 7.20 ± 0.20 and 9.10 ± 0.05, their distances are estimated to be (930 ± 30) pc and (3515 ± 60) pc, respectively. Also, we have calculated their projected distances (X⨀ and Y⨀) to the Galactic plane and the projected distance Z⨀ from the Galactic plane. The luminosity and mass functions of SAI 24 and SAI 94 clusters were outlined; accordingly, the masses were calculated to be (285 ± 17) M⨀ and (317 ± 18) M⨀, respectively. Finally, we concluded that these two clusters are dynamically relaxed according to our estimation of their dynamical evolution parameter τ as a function of their crossing time Tcross. The evaporation time τev as a function of their relaxation time Trelax is about 6.18 Myr and 25.38 Myr for SAI 24 and SAI 94, respectively.

Keywords

• Techniques: photometric
• Open clusters and associations: individual: SAI 24, SAI 94