Query : 2023A&A...671L..10N

2023A&A...671L..10N - Astronomy and Astrophysics, volume 671, L10 (2023/3-1)

Evidence of an age gradient along the line of sight in the nuclear stellar disc of the Milky Way.


Abstract (from CDS):

Context. The nuclear stellar disc (NSD) is a flat dense stellar structure at the heart of the Milky Way. Recent work has shown that analogous structures are common in the nuclei of external spiral galaxies, where there is evidence of an age gradient that indicates that they form inside-out. However, the characterisation of the age of the NSD stellar population along the line of sight is still missing due to its extreme source crowding and the high interstellar extinction towards the Galactic centre.
Aims. We aim to characterise the age of the stellar population at different average Galactocentric NSD radii to investigate for the first time the presence of an age gradient along the line of sight.
Methods. We selected two groups of stars at different NSD radii via their different extinction and proper motion distribution. We analysed their stellar population by fitting their de-reddened Ks luminosity functions with a linear combination of theoretical models.
Results. We find significant differences in the stellar population at different NSD radii, indicating the presence of an age gradient along the line of sight. Our sample from the closest edge of the NSD contains a significant fraction (∼40% of its total stellar mass) of intermediate-age stars (2-7 Gyr) that is not present in the sample from stars deeper inside the NSD, in which ∼90% of the stellar mass is older than 7 Gyr. Our results suggest that the NSD age distribution is similar to the one found in external galaxies and they imply that bar-driven processes observed in external galaxies are similarly at play in the Milky Way.

Abstract Copyright: © The Authors 2023

Journal keyword(s): Galaxy: nucleus - Galaxy: center - Galaxy: structure - dust - extinction - infrared: stars - proper motions

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 14463 0
2 NAME Sgr B1 MoC 17 47 02.0 -28 31 57           ~ 165 0
3 NAME Galactic Bar reg ~ ~           ~ 1224 0
4 NAME Galactic Bulge reg ~ ~           ~ 4309 0

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