Kinematics of classical Cepheids in the Nuclear Stellar Disk

TL;DR

This study measures the radial velocities of classical Cepheids near the Galactic Center to understand their orbits and origins within the Nuclear Stellar Disk, providing insights into the Galaxy's structure and stellar evolution.

Contribution

First measurement of Cepheid radial velocities near the Galactic Center, indicating their formation within the Nuclear Stellar Disk and their orbital characteristics.

Findings

Cepheids orbit within the Nuclear Stellar Disk

Three of the Cepheids' velocities suggest in-situ formation

Simulation supports their formation as young stars in the Disk

Abstract

Classical Cepheids are useful tracers of the Galactic young stellar population because their distances and ages can be determined from their period-luminosity and period-age relations. In addition, the radial velocities and chemical abundance of the Cepheids can be derived from spectroscopic observations, providing further insights into the structure and evolution of the Galaxy. Here, we report the radial velocities of classical Cepheids near the Galactic Center, three of which were reported in 2011, the other reported for the first time. The velocities of these Cepheids suggest that the stars orbit within the Nuclear Stellar Disk, a group of stars and interstellar matter occupying a region of 200 pc around the Center, although the three-dimensional velocities cannot be determined until the proper motions are known. According to our simulation, these four Cepheids formed within the Nuclear Stellar Disk like younger stars and stellar clusters therein.