# Tracing the Galactic disk from the kinematics of Gaia Cepheids

**Authors:** Xiaoyue Zhou, Xiaodian Chen, Licai Deng, Shu Wang  
**arXiv:** [2402.15782](https://arxiv.org/abs/2402.15782)  
**Date:** 2024-02-24  
**Summary page:** https://www.summarizepaper.com/en/paper/2402.15782v1/

## Key points

- Classical Cepheids (CCs) are valuable tools for understanding the structure and dynamics of the Milky Way disk.
- Gaia Data Release 3 provides line-of-sight velocity information for Galactic CCs, enabling a deeper exploration of the galaxy's kinematics.
- Recent study by Xiaoyue Zhou et al. determined three-dimensional velocities of 2057 CCs relative to the Galactic center, revealing intricate motions within the Milky Way.
- Significant differences in $V_{R}$ and $V_{\phi}$ velocities between northern and southern warp regions suggest connections to warp precession or structural asymmetries, warranting further investigation.
- Vertical velocities of CCs offer a robust constraint on warp precession rates, emphasizing their importance in studying galactic dynamics.
- CCs located at distances between 12-14 kpc provide an optimal sample for accurately determining the Galactic warp precession rate.
- A warp precession rate of $\omega = 4.9\pm1.6$ km s$^{-1}$ kpc$^{-1}$ at 13 kpc was derived, supporting a model with a relatively low precession rate in the Milky Way's warp.
- Continued efforts to gather more kinematic information on CCs can refine our understanding of the Milky Way's structure and evolution by combining observational data with theoretical models.

## Summary

Classical Cepheids (CCs) have long been recognized as valuable tools for understanding the structure and dynamics of the Milky Way disk. With the release of Gaia Data Release 3, a wealth of line-of-sight velocity information for Galactic CCs has become available, presenting an unprecedented opportunity to delve into the kinematics of our galaxy. In a recent study by Xiaoyue Zhou et al., the three-dimensional velocities of 2057 CCs relative to the Galactic center were determined, shedding light on the intricate motions within the Milky Way. By projecting these velocities onto the XY plane of the Galactic disk, significant differences in $V_{R}$ and $V_{\phi}$ velocities between the northern and southern warp regions were observed. This discrepancy hints at potential connections to warp precession or asymmetries in the warp structure, prompting further investigation into these phenomena. Notably, it was found that vertical velocities of CCs offer a more robust constraint on warp precession rates compared to line of nodes angles, emphasizing their importance in unraveling galactic dynamics. Focusing on CCs located at distances between 12-14 kpc, it was determined that they constitute an optimal sample for accurately determining the Galactic warp precession rate. Leveraging spatial structure parameters from previous work by Chen et al., a warp precession rate of $\omega = 4.9\pm1.6$ km s$^{-1}$ kpc$^{-1}$ at 13 kpc was derived, supporting a model with a relatively low precession rate in the Milky Way's warp. Looking ahead, continued efforts to gather more kinematic information on CCs hold promise for refining our understanding of the Milky Way's structure and evolution. By combining observational data with theoretical models, astronomers can further elucidate the complex dynamics at play within our galaxy and deepen our insights into its formation and development over cosmic timescales.