| Abstract : | Carbon stars represent a distinctive class of objects characterized by prominent absorption bands arising from various carbon molecules in their spectra. Their unique surface chemical characteristics have made carbon stars a subject of significant interest in the realm of stellar spectroscopic research. These stars are categorized into various groups, including CH,CN,C-R,and C-J stars,based on their distinct spectral attributes. Although many high-resolution spectroscopic analysis results are available for CH,and CN stars, detailed studies on C-R stars are quite scanty in literature. Previous studies have identified the objects HE 1104−0957,and HE 1205-0521 as C-R stars based on low-resolution spectroscopic analysis. This work presents a high-resolution spectroscopic follow-up of these objects with a primary goal to understand their surface chemical composition and hence to probe their possible progenitors. Surprisingly, our analysis shows that both HE 1104−0957,and HE 1205-0521 are very metal-poor ([Fe/H]<-2) with notably enhanced r-process elements which are not expected for C-R stars, a group typically characterized by near-solar heavy element abundances and near solar metallicity. Since the program stars show similar surface chemical compositions and spectral features as expected for Carbon-Enhanced Metal-Poor (CEMP) stars,we have checked various diagnostic elemental abundance ratios estimated in these objects with that of various CEMP sub-groups. However, these two stars do not meet any of the classification criteria of the CEMP stars. The kinematic profiles and surface chemical compositions of these stars do not support their classification as halo stars as well, suggesting that they likely originated in a neighboring galaxy. In this talk, I will be presenting some of the interesting results of our high-resolution spectroscopic analysis of HE 1104−0957, and HE 1205-0521. |
