Rediscovering the Galactic outer disk with LAMOST data

Abstract

From the derived stellar density profile using LAMOST giant stars, we find that the Galactic disk does not show truncation or break, but smoothly transit to the halo from 19 kpc. The scale length of the outer disk is only $1.6\pm 0.1$\,kpc, substantially smaller than previous results. This implies that the shapes of the inner and outer disk are different. Meanwhile, the disk flaring is not only found in older populations, but also in younger population. Moreover, the vertical oscillations of the disk are identified in a wide range or $R$ from 8 to 14 kpc. We also find that the velocity dispersion profile as a function of the Galactocentric radius is flat with scale length of $26.3\pm 3.2$\,kpc. We confirm that the radial velocity profile in outer disk is significantly affected by asymmetric motion. The bar with either a slower or a faster pattern speed can induce the similar radial asymmetric motion.

7 pages, 7 figures, "Rediscovering our Galaxy" Proceedings IAU Symposium No. 334, 2017, C. Chiappini, I. Minchev, E. Starkenberg, M. Valentini, eds

References in corpus (11)

• galpy: A Python Library for Galactic Dynamics
• Outer structure of the Galactic warp and flare: explaining the Canis Major over-density
• Rings and Radial Waves in the Disk of the Milky Way
• Radial and vertical flows induced by galactic spiral arms: likely contributors to our "wobbly Galaxy''
• The K giant stars from the LAMOST survey data I: identification, metallicity, and distance
• Flare in the Galactic stellar outer disc detected in SDSS-SEGUE data
• The Edge of the Milky Way Stellar Disk Revealed Using Clump Giant Stars as Distance Indicators
• The Vertical Structure and Kinematics of Grand Design Spirals
• A resonant feature near the Perseus arm revealed by red clump stars
• The local spiral arm in the LAMOST-Gaia common stars?
• Torus Models of the Outer Disc of the Milky Way using LAMOST Survey Data

Cited by in corpus (5)

• An intuitive 3D map of the Galactic warp's precession traced by classical Cepheids
• More than just a wrinkle: A wave-like pattern in radial velocity vs. angular momentum from Gaia Data
• Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. II. 3D asymmetrical kinematics of mono-age populations in the disk between 6$-14$ \,kpc
• Modeling of Spiral Structure in a Multi-Component Milky~Way-Like Galaxy
• Kinematic-Chemical analysis and Time tagging for the Diagonal Ridge Structure of the Galactic Outer Disk with LAMOST Red Giant Branch Stars