A Catalog of 1,408 Carbon-Enhanced Metal-Poor Stars from LAMOST DR11

Abstract

Metal-poor (MP) stars are important targets for investigating the chemical evolution of the early universe. Among them, Carbon-Enhanced Metal-Poor (CEMP) stars have attracted extensive attention due to their rarity and astrophysical significance. Owing to their low occurrence rate, the identification of MP stars and CEMP stars remains a task of considerable scientific value. In this study, we investigate the search for CEMP stars based on the low-resolution stellar spectra from LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) DR11 and propose a deep-learning-based approach for this purpose. By analyzing the LAMOST DR11 spectral library, we identify 1,408 CEMP star candidates. For ease of reference and further use, we provide the estimated stellar parameters for these objects, including $T_\texttt{eff}$, $\log~g$, [Fe/H], and [C/H].

Figures (8)

• Figure 1: Comparison of four CEMP stellar spectra before and after continuum normalization, illustrating the preservation of the CH G-band (approximately 4280--4320 Å, shaded in purple) across a range of [C/Fe] values. The black curve shows the original flux, the red dashed line the fitted continuum, while the light gray horizontal dashed line indicates the reference continuum after normalization ($y=1.0$).
• Figure 2: The performance of parameter estimation. The horizontal axis represents the reference values and the vertical axis represents the estimated values. These results are computed from the test set. The black dashed lines represent the reference line for theoretical consistency, while the red dashed lines represent the 3$\sigma$ reference lines. The $\mu$, $\sigma$ are the mean and standard deviation of the difference between the parameter estimation and its corresponing reference on test spectra. MAE is the mean absolute error/difference between the parameter estimation and its corresponing reference on test spectra.
• Figure 3: (a) Distribution of 1,408 CEMP candidates in the parameter space; (b) Occurrence rate of the CEMP candidates, where bins with sample sizes exceeding 80 are not shown. [C/Fe] = [C/H] − [Fe/H].
• Figure 4: Comparison of the physical parameters of the CEMP candidates identified in this work with the corresponding parameters from Gaia DR3. The x-axis represents the parameter estimates obtained in this work, while the y-axis shows those derived from Gaia DR3. The color intensity indicates the data point density, with brighter colors corresponding to higher densities. The black dashed line denotes the line of theoretical consistency ($y = x$), and the red dashed line represents the $3\sigma$ deviation reference. The $\mu_r$ and $\sigma_r$ correspond to the mean and standard deviation of the differences between the two catalogs, respectively, while MAD denotes the mean absolute difference between the two catalogs.
• Figure 5: Distribution of [C/Fe] versus classification confidence for CEMP candidates. Different colors indicate high, medium, and low confidence levels.