The Galactic warp revealed by Gaia DR2 kinematics. (13th August 2018)

• Record Type: Journal Article
• Authors: Poggio, E; Drimmel, R; Lattanzi, M G; Smart, R L; Spagna, A; Andrae, R; Bailer-Jones, C A L; Fouesneau, M; Antoja, T; Babusiaux, C; Evans, D W; Figueras, F; Katz, D; Reylé, C; Robin, A C; Romero-Gómez, M; Seabroke, G M
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 481:Number 1(2018:Nov.)
• Page Start: L21
• Page End: L25
• Publication Date: 2018-08-13
• Subjects: stars: kinematics and dynamics -- Galaxy: disc -- Galaxy: kinematics and dynamics -- Galaxy: structure; Astronomy -- Research -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnrasl/sly148
• Languages: English
• ISSNs: 1745-3933

Abstract

ABSTRACT: Using Gaia DR2 astrometry, we map the kinematic signature of the Galactic stellar warp out to a distance of 7 kpc from the Sun. Combining Gaia DR2 and 2-Micron All Sky Survey photometry, we identify, via a probabilistic approach, $599 \, 494$ upper main sequence (UMS) stars and $12\, 616\, 068$ giants without the need for individual extinction estimates. The spatial distribution of the UMS stars clearly shows segments of the nearest spiral arms. The large-scale kinematics of both the UMS and giant populations show a clear signature of the warp of the Milky Way, apparent as a gradient of 5–6 km s −1 in the vertical velocities from 8 to 14 kpc in Galactic radius. The presence of the signal in both samples, which have different typical ages, suggests that the warp is a gravitationally induced phenomenon.