Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Gaia Collaboration - (Author)
  • Research Group for Astronomy
  • National Institute for Astrophysics
  • University of Barcelona
  • Universidad de Antofagasta
  • University of Strasbourg
  • Observatoire de la Cote d'Azur
  • Osservatorio Astronomico di Capodimonte
  • Max Planck Institute for Astronomy
  • Royal Observatory of Belgium
  • Leiden University
  • Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
  • Radagast Solutions
  • University of Groningen
  • Université de Toulouse
  • Astronomical Observatory of Padua
  • ESTEC - European Space Research and Technology Centre
  • Institute for Celestial Mechanics and Computation of Ephemerides
  • IPAG - Institute of Planetology and Astrophysics of Grenoble
  • Heidelberg University 
  • Université de Bordeaux
  • University of Cambridge
  • University of Geneva
  • European Space Astronomy Centre
  • European Space Agency - ESA
  • TUD Dresden University of Technology
  • Lund University
  • Centre national d'études spatiales
  • Université libre de Bruxelles (ULB)
  • Belgian National Fund for Scientific Research
  • Osservatorio Astrofisico Di Arcetri, Florence

Abstract

Context. With the most recent Gaia data release, the number of sources with complete 6D phase space information (position and velocity) has increased to well over 33 million stars, while stellar astrophysical parameters are provided for more than 470 million sources, and more than 11 million variable stars are identified. Aims. Using the astrophysical parameters and variability classifications provided in Gaia DR3, we selected various stellar populations to explore and identify non-axisymmetric features in the disc of the Milky Way in configuration and velocity space. Methods. Using more about 580 000 sources identified as hot OB stars, together with 988 known open clusters younger than 100 Myr, we mapped the spiral structure associated with star formation 4'5 kpc from the Sun. We selected over 2800 Classical Cepheids younger than 200 Myr that show spiral features extending as far as 10 kpc from the Sun in the outer disc. We also identified more than 8.7 million sources on the red giant branch (RGB), of which 5.7 million have line-of-sight velocities. This later sample allows the velocity field of the Milky Way to be mapped as far as 8 kpc from the Sun, including the inner disc. Results. The spiral structure revealed by the young populations is consistent with recent results using Gaia EDR3 astrometry and source lists based on near-infrared photometry, showing the Local (Orion) Arm to be at least 8 kpc long, and an outer arm consistent with what is seen in HI surveys, which seems to be a continuation of the Perseus arm into the third quadrant. The subset of RGB stars with velocities clearly reveals the large-scale kinematic signature of the bar in the inner disc, as well as evidence of streaming motions in the outer disc that might be associated with spiral arms or bar resonances. A local comparison of the velocity field of the OB stars reveals similarities and differences with the RGB sample. Conclusions. This cursory study of Gaia DR3 data shows there is a rich bounty of kinematic information to be explored more deeply, which will undoubtedly lead us to a clearer understanding of the dynamical nature of the non-axisymmetric structures of the Milky Way.

Details

Original languageEnglish
Article numberA37
Pages (from-to)1-35
Number of pages35
JournalAstronomy and Astrophysics
Volume674
Publication statusPublished - 1 Jun 2023
Peer-reviewedYes

External IDs

ORCID /0000-0002-9533-2168/work/168205406
ORCID /0000-0003-4682-7831/work/168206664
ORCID /0000-0001-6967-8707/work/168207053

Keywords

Keywords

  • Catalogs, Galaxy: bulge, Galaxy: disk, Galaxy: kinematics and dynamics, Galaxy: structure