SED Analysis of the Old Open Cluster NGC 188

SED Analysis of the Old Open Cluster NGC 188
Deniz Cennet Dursun, Seval Tac{s}demir, Seliz Koc{c}, Srishti .Iyer
arXiv:2404.13115v1 Announce Type: new
Abstract: In this study, we investigate the fundamental astrophysical parameters of the old open cluster NGC 188 through two complementary methods: isochron-fitting and spectral energy distribution (SED) analysis. Using photometric, astrometric, and spectroscopic data from the Gaia Data Release 3, we identify 868 most likely member stars with membership probabilities $P geq 0.5$. The mean proper-motion components and trigonometric parallaxes of the cluster are derived as ($mu_{alpha}cos delta$, $mu_{delta}$) = (-$2.314 pm 0.002$, -$1.022 pm 0.002$) mas yr$^{-1}$ and $varpi = 0.550 pm 0.023$, respectively. From this initial selection of high probable member stars, we proceed with the determination of astrophysical parameters using the isochron-fitting method. Simultaneously estimating the colour excess, distance, and age of the cluster, we employee PARSEC isochrones to observational data on Gaia based colour-magnitude diagrams. These findings were obtained as $E(G_{BP}-G_{RP})=0.066pm 0.012$ mag, $d=1806 pm21$ pc, and $t=7.65 pm 1.00$ Gyr, respectively. Additionally, we identify and detected 19 previously confirmed blue straggler stars within NGC 188. Subsequently, we performed SED analyses for 412 out of the 868 cluster members. We obtained colour excess, distance and age of the cluster as $E(B-V)=0.034pm 0.030$ mag, $d=1854pm 148$ pc, and $t=7.78pm 0.23$ Gyr, respectively. The analysis of member stars was revealed patterns of extinction in the $V$-band, with higher values of A(V) observed in the lower right quadrant of the cluster. By comparing our results of SED analysis with models of stellar evolution, particularly in terms of temperature and surface gravity, we confirm agreement with theoretical predictions. This comprehensive investigation sheds light on the astrophysical properties of NGC 188, contributing to our understanding of stellar evolution within open clusters.arXiv:2404.13115v1 Announce Type: new
Abstract: In this study, we investigate the fundamental astrophysical parameters of the old open cluster NGC 188 through two complementary methods: isochron-fitting and spectral energy distribution (SED) analysis. Using photometric, astrometric, and spectroscopic data from the Gaia Data Release 3, we identify 868 most likely member stars with membership probabilities $P geq 0.5$. The mean proper-motion components and trigonometric parallaxes of the cluster are derived as ($mu_{alpha}cos delta$, $mu_{delta}$) = (-$2.314 pm 0.002$, -$1.022 pm 0.002$) mas yr$^{-1}$ and $varpi = 0.550 pm 0.023$, respectively. From this initial selection of high probable member stars, we proceed with the determination of astrophysical parameters using the isochron-fitting method. Simultaneously estimating the colour excess, distance, and age of the cluster, we employee PARSEC isochrones to observational data on Gaia based colour-magnitude diagrams. These findings were obtained as $E(G_{BP}-G_{RP})=0.066pm 0.012$ mag, $d=1806 pm21$ pc, and $t=7.65 pm 1.00$ Gyr, respectively. Additionally, we identify and detected 19 previously confirmed blue straggler stars within NGC 188. Subsequently, we performed SED analyses for 412 out of the 868 cluster members. We obtained colour excess, distance and age of the cluster as $E(B-V)=0.034pm 0.030$ mag, $d=1854pm 148$ pc, and $t=7.78pm 0.23$ Gyr, respectively. The analysis of member stars was revealed patterns of extinction in the $V$-band, with higher values of A(V) observed in the lower right quadrant of the cluster. By comparing our results of SED analysis with models of stellar evolution, particularly in terms of temperature and surface gravity, we confirm agreement with theoretical predictions. This comprehensive investigation sheds light on the astrophysical properties of NGC 188, contributing to our understanding of stellar evolution within open clusters.