A first glimpse at the line-of-sight structure of the Milky Way's nuclear stellar disc

Abstract

The nuclear stellar disc (NSD) is a dense stellar structure at the centre of our Galaxy. Given its proximity, it constitutes a unique laboratory to understand other galactic nuclei. Nevertheless, the high crowding and extinction hamper its study, and even its morphology and kinematics are not yet totally clear. In this work we use NSD red clump stars, whose intrinsic properties are well known, to trace the kinematics of the NSD and to compute the distance and extinction towards the edges of the NSD. We used publicly available proper motion and photometric catalogues of the NSD to distinguish red clump stars by using a colour-magnitude diagram. We then applied a Gaussian mixture model to obtain the proper motion distribution, and computed the extinction and distance towards stars with different kinematics. We obtained that the proper motion distributions contain NSD stars rotating eastwards and westwards, plus some contamination from Galactic bulge/bar stars, in agreement with previous work. We computed the distance and extinction towards the eastward- and westward-moving stars and concluded that the latter are $\sim 300$ pc beyond, indicating a similar structure along and across the line of sight, and consistent with an axisymmetric structure of the NSD. Moreover, we found that the extinction within the NSD is relatively low and accounts for less than 10 % of the total extinction of the stars belonging to the farthest edge of the NSD.

Accepted for publication in A&A. 7 pages, 6 figures

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Cited by in corpus (6)

• Evidence of an age gradient along the line of sight in the nuclear stellar disc of the Milky Way
• Smooth kinematic and metallicity gradients reveal that the Milky Way's nuclear star cluster and disc might be part of the same structure
• Metallicity-dependent kinematics and orbits in the Milky Way's nuclear stellar disc
• Chemical Evolution in Nuclear Stellar Discs
• The Galactic Center with Roman
• 3D CMZ V: A new orbital model of our Galaxy's Center, informed by data across the electromagnetic spectrum