Hierarchical Absorption in LAMOST low Resolution Normalized Spectra

TL;DR

This paper demonstrates the detection of at least 12 stellar clusters in LAMOST low-resolution spectra by analyzing spectral line patterns, revealing hierarchical absorption effects that could help identify substructures in the Milky Way.

Contribution

It introduces a method leveraging collective spectral line effects to detect hierarchical absorption in low-resolution spectra, aiding in substructure identification.

Findings

At least 12 clusters identified in LAMOST spectra

Hierarchical absorption effects observed in spectral data

Method reduces degeneracy in chemical abundance analysis

Abstract

According to the hierarchical clustering scenario, galaxies like the Milky Way form hierarchically, and many supporting evidences have been found in the Galactic halo. However, most stars in the Milky Way are disk stars. Disk stars have almost lost their spatial distribution and kinematic features at birth, retaining solely chemical signatures. Identifying such substructures using abundances of iron or light elements is difficult due to their high degeneracy. Heavy elements, especially neutron capture elements have limited sources so have lower degeneracy, but spectral line fitting of these elements is tough, requiring mid to high resolution spectra, which are currently limited in sample size. This work utilizes the collective effect of many spectral lines from several elements, especially neutron capture elements to weaken the degeneracy of [Fe/H]. The analysis suggests the presence of at least 12 clusters, due to the hierarchical absorption in LAMOST low resolution normalized Spectra. More detailed work is needed to ascertain whether this hierarchical absorption is natural.