Tracing Early Enrichment Pathways: Chemical and Chemodynamical Analysis of Two CEMP-no Stars*

Abstract We present a detailed high-resolution spectroscopic and chemodynamic analysis of two carbon stars, HE 1148−0037 and HE 1246−1344, using SUBARU High Dispersion Spectrograph spectra ( R ∼ 50,000). Our analysis confirms that both stars are extremely metal-poor and belong to the Carbon-Enhanced Metal-Poor (CEMP)-no class ([C/Fe] > 0.70 and [Ba/Fe] < −1.0). Both of the stars are found to be group II CEMP-no stars in the A (C) versus [Fe/H] diagram. While both stars exhibit slightly enhanced α -elements (Ca, Sc), their Mg, Fe-peak, and neutron-capture element abundances show distinct trends, indicating different progenitor pathways. From [O/Fe] and [Sr/Ba] ratios, we identify both metal-poor asymptotic giant branch stars and fast-rotating massive stars as potential progenitors. Further elemental abundance analysis suggests a multienrichment origin for these stars. Kinematic analysis reveals that HE 1148−0037 belongs to the halo, with a spatial velocity of 464.99 ± 14 km s −1 . Orbital calculations show that HE 1148−0037 follows a retrograde orbit and is associated with the high-energy retrograde halo, likely a member of the I’itoi substructure. In contrast, HE 1246−1344 follows a prograde orbit and is linked to Gaia-Sausage/Enceladus.