Exploring the structure and kinematics of the Milky Way through A stars

Abstract

Despite their relatively high intrinsic brightness and the fact that they are more numerous than younger OB stars and kinematically colder than older red giants, A-type stars have rarely been used as Galactic tracers. They may, in fact, be used to fill the age gap between these two tracers, thereby allowing us to study the transition between them. We analyse Galactic disc structure and kinematic perturbations up to 6 kpc from the Sun based on observations of A-type stars. This work presents a catalogue of A-type stars selected using the IGAPS photometric survey. It covers the Galactic disc within $30^o\le l\le 215^o$ and $|b|\le 5^o$ up to a magnitude of $r\le 19$ mag with about 3.5 million sources. We used Gaia Data Release 3 parallaxes and proper motions, as well as the line-of-sight velocities, to analyse the large-scale features of the Galactic disc. We carried out a study of the completeness of the detected density distributions, along with a comparison between the $b<0^o$ and $b>0^o$ regions. Possible biases caused by interstellar extinction or by the usage of some kinematic approximations were examined as well. We find stellar overdensities associated with the Local and the Perseus spiral arms, as well as with the Cygnus region. A-type stars also provide kinematic indications of the Galactic warp towards the anticentre, which displays a median vertical motion of ~6-7 km/s at a Galactocentric radius of R=14 kpc. It starts at R=12 kpc, which supports the scenario where the warp begins at larger radii for younger tracers when compared with other samples in the literature. We also detect a region with downward mean motion extending beyond 2 kpc from the Sun towards $60^o<l<75^o$ that may be associated with a compression breathing mode. Furthermore, A-type stars reveal very clumpy inhomogeneities and asymmetries in the $V_Z$-$V_{\varphi }$ velocity space plane.

arXiv comment15 pages, 13 figures. Accepted for publication in Astronomy & Astrophysics

References in corpus (58)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 3: Summary of the content and survey properties
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• Co-formation of the Galactic disc and the stellar halo
• Gaia Early Data Release 3: Photometric content and validation
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Gaia Data Release 2: using Gaia parallaxes
• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• PARSEC evolutionary tracks of massive stars up to $350M_{\odot }$ at metallicities 0.0001$\le Z\le$0.04
• Painting a portrait of the Galactic disc with its stellar clusters
• Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
• Estimating distances from parallaxes
• A dynamically young and perturbed Milky Way disk
• Gaia broad band photometry
• Vertical waves in the solar neighbourhood in Gaia DR2
• Gaia Data Release 3 Properties and validation of the radial velocities
• Improving the open cluster census. II. An all-sky cluster catalogue with Gaia DR3
• Kinematics and history of the solar neighbourhood revisited
• A standard stellar library for evolutionary synthesis. III. Metallicity calibration
• The Vertical Structure of the Outer Milky Way HI Disk
• Gaia Data Release 3: Astrophysical parameters inference system (Apsis) I -- methods and content overview
• Spectrophotometric Libraries, Revised Photonic Passbands and Zero-points for UBVRI, Hipparcos and Tycho Photometry
• The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation
• The Spiral Structure of the Outer Milky Way in Hydrogen
• The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution
• The Proper Motion of Sagittarius A*: III. The Case for a Supermassive Black Hole
• Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way
• Galactic spiral structure revealed by Gaia EDR3
• An intuitive 3D map of the Galactic warp's precession traced by classical Cepheids
• Three-Dimensional Distribution of the ISM in the Milky Way Galaxy: III. The Total Neutral Gas Disk
• The Galactic warp revealed by Gaia DR2 kinematics
• A 3D extinction map of the Northern Galactic Plane based on IPHAS photometry
• Gaia Early Data Release 3: The Galactic anticentre
• Evolution over time of the Milky Way's disc shape
• The Gaia reference frame for bright sources examined using VLBI observations of radio stars
• Kinematics of the local disk from the RAVE survey and the Gaia first data release
• The Alma catalog of OB stars. II. A cross-match with Gaia DR2 and an updated map of the solar neighbourhood
• Early-A stars from IPHAS, and their distribution in and around the Cyg OB2 association
• Gaia kinematics reveal a complex lopsided and twisted Galactic disc warp
• Full 5D characterisation of the Sagittarius stream with Gaia DR2 RR Lyrae
• The Structure of the Outer Galactic Disc as revealed by IPHAS early A Stars
• IGAPS: the merged IPHAS and UVEX optical surveys of theNorthern Galactic Plane
• Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas
• Gaia Data Release 3: Hot-star radial velocities
• First detection of the field star overdensity in the Perseus arm
• Non-circular Motions in the Outer Perseus Spiral Arm
• The spiral potential of the Milky Way
• Marginal likelihoods of distances and extinctions to stars: computation and compact representation
• A and F stars as probes of outer Galactic disc kinematics
• A study of full space motions of outer Galactic disk A and F stars in two deep pencil-beams

Cited by in corpus (8)

• Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost
• Ripples spreading across the Galactic disc. Interplay of direct and indirect effects of the Sagittarius dwarf impact
• Growing Local arm inferred by the breathing motion
• Parallax-based Distances to Galactic Hii Regions: Nearby Spiral Structure
• The Alma catalogue of OB stars. III. A cross-match with Gaia DR3 and an extension based on new spectral classifications
• RR Lyrae stars trace the Milky Way warp
• The large-scale kinematics of young stars in the Milky Way disc: first results from SDSS-V
• Azimuthal Misalignments in Stellar Warp Structure as Dynamical Tracers of Mergers in Milky Way-like Galaxies