Kinematic Detection of the Galactic Nuclear Disc

TL;DR

This paper reports the detection of a stellar nuclear disc in the Milky Way using infrared spectroscopy, revealing its kinematic properties, extent, and possible structural features.

Contribution

First detection of the Galactic nuclear stellar disc through line-of-sight stellar kinematics using APOGEE infrared data.

Findings

Stellar nuclear disc has rotation velocity ~120 km/s.

Disc is kinematically cool with ~50 pc vertical extent.

Evidence for a truncation at ~150 pc and a possible overdensity.

Abstract

We report the detection of the Galactic nuclear disc in line-of-sight kinematics of stars, measured with infrared spectroscopy from APOGEE. This stellar component of the nuclear disc has an extent and rotation velocity V ~ 120kms comparable to the gas disc in the central molecular zone. The current data suggest that this disc is kinematically cool and has a small vertical extent of order 50pc. The stellar kinematics suggest a truncation radius/steep decline of the stellar disc at a galactocentric radius R ~ 150pc, and provide tentative evidence for an overdensity at the position of the ring found in the molecular gas disc.