Our solar neighborhood has many asymmetries, such as snail shape and ridge shape. Up to now, our astronomers are still lack of clear and enough information about the famous ridge structure.

Recently, a research team, led by LAMOST Fellow Dr. Hai-Feng Wang collaborating with China and Spain astronomers, performed the detailed Chemo-Dynamical analysis of the diagonal ridge feature and presented a timing tagging for it with the help of LAMOST data.

Researchers recovered the ridge pattern and found that this feature is presented from very young to very old stars. Meanwhile, some ridge features are also revealed in the chemical space.

“We found that there might be two kinds of ridge patterns with different dynamical origins and evolutions based on the statistical analysis”, said Dr. Hai-Feng Wang, the first author of the paper.

The viewpoint of the two kinds of origins is also supported, via recent emails, by Prof. Joss Bland-Hawthorn, an astronomer from the University of Sydney of Australia.

“Some previous works pointed out clearly that the spiral arms in our home galaxy can generate ridges accompanied with the points that different ridges could have originated from different scenarios, but if they want to unify the global picture, the well-known Sagittarius satellite perturbation is favored,” said Dr. Martín López-Corredoira, the co-author of this paper.

“In this work, we actually detect the similar signals as shown in some previous works,” said Dr. Hai-Feng Wang.

“All these evidence might support that both the spiral arms or internal mechanism and Sgr perturbations or external mechanism are important contributors for this structure,” said Dr. Martín López-Corredoira.

Referee of this paper pointed out that “These results provide additional constraints on the theoretical models, and encourage further theoretical studies to distinguish these scenarios based on the new observational constraints.”

The paper recently is published by The Astrophysical Journal on Oct 13, 2020.

Figure 1: Ridge maps are shown, the top one is the ridge structure in the eyes of astronomers, the bottom one is the ridge shape in our lives. (Credit: Hai-Feng Wang)

This paper link can be accessed at https://iopscience.iop.org/article/10.3847/1538-4357/abb3c8