Rediscovering the Milky Way with orbit superposition approach and APOGEE data II. Chrono-chemo-kinematics of the disc

Autor(en)

Sergey Khoperskov, Matthias Steinmetz, Misha Haywood, Glenn van de Ven, Davor Krajnovic, Bridget Ratcliffe, Ivan Minchev, Paola Di Matteo, Nikolay Kacharov, Léa Marques, Marica Valentini, Roelof S. de Jong

Abstrakt

The stellar disc is the dominant luminous component of the Milky Way (MW). Although our understanding of its structure is rapidly expanding due to advances in large-scale stellar surveys, our picture of the MW disc remains substantially obscured by selection functions and incomplete spatial coverage of observational data. In this work, we present the comprehensive chrono-chemo-kinematic structure of the MW disc, recovered using a novel orbit superposition approach combined with data from APOGEE DR 17. We detect periodic azimuthal metallicity variations within 6-8 kpc with an amplitude of 0.05-0.1 dex peaking along the bar major axis. The radial metallicity profile of the MW also varies with azimuth, displaying a pattern typical among other disc galaxies: a decline outside the solar radius and an almost flat profile in the inner region, attributed to the presence of old, metal-poor high-{\alpha} populations, which comprise about 40% of the total stellar mass. The geometrically defined thick disc and the high-{\alpha} populations have comparable masses, with differences in their stellar population content, which we quantify using the reconstructed 3D MW structure. The well-known [{\alpha}/Fe]-bimodality in the MW disc, once weighted by stellar mass, is less pronounced at a given metallicity for the whole galaxy but distinctly visible in a narrow range of galactic radii (5-9 kpc), explaining its relative lack of prominence in external galaxies and galaxy formation simulations. Analysing a more evident double age-abundance sequence, we construct a scenario for the MW disc formation, advocating for an inner/outer disc dichotomy genetically linked to the MW's evolutionary stages. In this picture, the extended solar vicinity is a transition zone that shares chemical properties of both the inner (old age-metallicity sequence) and outer discs (young age-metallicity sequence).

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Leibniz-Institut für Astrophysik Potsdam, Observatoire de Paris, Universität Potsdam

Journal

Astronomy & Astrophysics

Anzahl der Seiten

36

ISSN

0004-6361

Publikationsdatum

11-2024

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/403fded4-3db4-4331-bc6a-31795acc749b