High-resolution spectroscopy of HE 0225?0546 and HE 1153?0518: probing the progenitors through abundance patterns and kinematics
stars: abundances; stars: carbon; stars: chemically peculiar; stars: kinematics and dynamics; stars: Population II
We present the results of a high-resolution (SUBARU/HDS, R ? 50 000) spectroscopic study of two metal-poor stars, HE 0225 ?0546 and HE 1153 ?0518. This marks the first such detailed analysis for both objects. Our findings reveal that HE 0225 ?0546 is extremely metal-poor with [Fe/H] ??3.03, while HE 1153 ?0518 is very metal-poor with [Fe/H] ??2.80. Both stars exhibit enhancements in carbon and neutron-capture elements and formally satisfy the criteria for carbon-enhanced metal- poor (CEMP) classification. Although their [Ba/Eu] and [La/Eu] ratios do not allow a secure assignment to any specific CEMP sub-class, the estimated [Ba/Eu] and [Eu/Fe] ratios indicate that both stars fall into the r-II star category. Distinct abundance patterns between the two stars suggest different nucleosynthetic histories. HE 0225 ?0546 shows strong enhancement in Fe-peak elements, while HE 1153 ?0518 is mildly deficient in the same. Both stars are ?-enhanced, though the level of enhancement varies. These results indicate pollution by multiple progenitor channels. Abundance ratios imply that HE 0225 ?0546 is likely enriched by fast-rotating massive stars (FRMS), whereas HE 1153 ?0518 shows signatures consistent with asymptotic giant branch (AGB) star enrichment. Kinematic analyses place both stars in the high-energy, prograde component of the Galactic halo. HE 0225 ?0546 has an apogalactic distance (rapo ) of ?31.8 kpc, placing it in the outer halo, while HE 1153 ?0518 lies closer to the boundary of the inner and outer halo with rapo ?13.8 kpc. Both stars show kinematic coherence with the Sagittarius substructure, suggesting a possible extragalactic origin. The Author(s) 2025. Published by Oxford University Press on behalf of Royal Astronomical Society.
Purandardas, Meenakshi; Aroli-Veettil, Sidharth; Ray, Shankar; Mathew, Blesson; Kartha, Sreeja S.; Sreeshma, N.M.; Haridas, Sreelakshmi
Monthly Notices of the Royal Astronomical Society;Volume;546;Issue;1;Article No.;staf2215;
https://doi.org/10.1093/mnras/staf2215 https://www.scopus.com/pages/publications/105028243223?origin=resultslist
Purandardas M., Department of Physics and Electronics, Christ (Deemed to be University), Bengaluru, 560029, India; Aroli-Veettil S., Instituto de Astrofica, Pontificia Universidad Catica de Chile, Vicu Mackenna 4860, Santiago, Chile; Ray S., Department of Physics and Electronics, Christ (Deemed to be University), Bengaluru, 560029, India; Mathew B., Department of Physics and Electronics, Christ (Deemed to be University), Bengaluru, 560029, India; Kartha S.S., Department of Physics and Electronics, Christ (Deemed to be University), Bengaluru, 560029, India; Sreeshma N.M., Department of Physics, Vimala college, Kerala, Thrissur, 680009, India; Haridas S., Department of Physics, Vimala college, Kerala, Thrissur, 680009, India