Spectroscopic and Dynamic Orbital Analyses of Metal-Poor and High Proper Motion Stars: I. HD\,8724 and HD\,195633 (2406.17776v1)

Abstract: In this study, spectral, age, kinematic, and orbital dynamical analyses were conducted on metal-poor and high proper-motion (HPM) stars, HD 8724 and HD 195633, selected from the Solar neighborhood. This analysis combines detailed abundance measurements, kinematics, and orbital dynamics to determine their origin. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters: $T_{\rm eff}=$4700$\pm$115 K, $\log g=$ 1.65$\pm$0.32 cgs, [Fe/H]=-1.59$\pm$0.04 dex, and a microturbulent velocity $\xi=$ 1.58$\pm$0.50 km s$^{\rm -1}$ for HD 8724 and $T_{\rm eff}=$6100$\pm$205 K, $\log g=$3.95$\pm$0.35 cgs, [Fe/H]=-0.52$\pm$0.05 dex, and $\xi=$1.26$\pm$0.50 km s$^{\rm -1}$ for HD 195633. The ages were estimated using a Bayesian approach (12.25 Gyr for HD 8724 and 8.15 Gyr for HD 195633). The escape scenarios of these stars from 170 candidate globular clusters (GCs) in the Galaxy were also investigated because of their chemical and physical differences (HPM and metal-poor nature). Accordingly, the calculated probability of encounter ($59\%$) for HD 8724 at a distance of five tidal radius suggests that star HD 8724 may have escaped from NGC 5139 ($\omega$ Cen), supported by its highly flattened orbit and may belong to a sub-population of this GC. Conversely, HD 195633's kinematics, age, and metal abundances point towards an escape from the bulge GC NGC 6356.