The Structure of the Outer Galactic Disc as revealed by IPHAS early A Stars

Abstract

This study is an investigation of the stellar density profile of the Galactic disc in the Anticentre direction. We select over 40,000 early A stars from IPHAS photometry in the Galactic longitude range 160 < l < 200 close to the equatorial plane (-1 < b < +1). We then compare their observed reddening-corrected apparent magnitude distribution with simulated photometry obtained from parameterised models in order to set constraints on the Anticentre stellar density profile. By selecting A stars, we are appraising the properties of a population only ~100 Myrs old. We find the stellar density profile of young stars is well fit to an exponential with length scale of (3020 \pm 120_{statistical} \pm 180_{systematic}) pc, which is comparable to that obtained in earlier studies, out to a Galactocentric radius of R_T = (13.0 \pm 0.5_{statistical} \pm 0.6_{systematic}) kpc. At larger radii the rate of decline appears to increase with the scale length dropping to (1200 \pm 300_{statistical} \pm 70_{systematic}) pc. This result amounts to a refinement of the conclusions reached in previous studies that the stellar density profile is abruptly truncated. The IPHAS A star data are not compatible with models that propose a sudden change in metallicity at R_G = 10 kpc.

11 pages, accepted for publication in MNRAS

References in corpus (25)

• The UKIDSS Galactic Plane Survey
• The structure of galactic disks: Studying late-type spiral galaxies using SDSS
• The Outer Disks of Early-Type Galaxies. I. Surface-Brightness Profiles of Barred Galaxies
• Color Profiles of Spiral Galaxies: Clues on Outer-Disk Formation Scenarios
• The evolution of the Galactic metallicity gradient from high-resolution spectroscopy of open clusters
• The Origin of the Light Distribution in Spiral Galaxies
• Old open clusters in the outer Galactic disk
• Abundance gradients in the Milky Way for alpha elements, Iron peak elements, Barium, Lanthanum and Europium
• Kinematics of the old stellar population at the Galactic Center
• The metallicity gradient of M 33: chemical abundances of HII regions
• Star formation in M33: multiwavelength signatures across the disk
• Initial Data Release from the INT Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS)
• Displacement of the Sun from the Galactic Plane
• Clustered star formation as a natural explanation of the Halpha cutoff in disc galaxies
• Revisiting two local constraints of the Galactic chemical evolution
• Search for associations containing young stars (SACY):II. Chemical abundances of stars in 11 young Associations in the Solar neighborhood
• The Abundance Gradient in the Extremely Faint Outer Disk of NGC 300
• The building up of the disk galaxy M33 and the evolution of the metallicity gradient
• High Spatial Resolution Galactic 3D Extinction Mapping with IPHAS
• Early-A stars from IPHAS, and their distribution in and around the Cyg OB2 association
• The UV-Excess Survey of the Northern Galactic Plane (UVEX)
• Cosmic Evolution of Stellar Disk Truncations: From z~1 to the Local Universe
• The Stellar Populations of M33's Outer Regions II: Deep ACS Imaging
• OB Stars in the Solar Neighborhood I: Analysis of their Spatial Distribution
• The origin of abundance gradients in the Milky Way: the predictions of different models

Cited by in corpus (29)

• Discovering the QCD Axion with Black Holes and Gravitational Waves
• The stellar population structure of the Galactic disk
• The age-metallicity structure of the Milky Way disk
• The Second Data Release of the INT Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS DR2)
• An Extremely Luminous and Variable Ultraluminous X-ray Source in the Outskirts of Circinus Observed with NuSTAR
• Evolution over time of the Milky Way's disc shape
• The Edge of the Milky Way Stellar Disk Revealed Using Clump Giant Stars as Distance Indicators
• Ejection velocities of high Galactic latitude runaway stars
• Partly burnt runaway stellar remnants from peculiar thermonuclear supernovae
• The edge of the young Galactic disc
• On Rings and Streams in the Galactic Anti-Center
• 3D Extinction Mapping Using Hierarchical Bayesian Models
• Disk stars in the Milky Way detected beyond 25 kpc from its center
• The time evolution of the Milky Way's oxygen abundance gradient
• Structure of the outer Galactic disc with Gaia-DR2
• A deep catalogue of classical Be stars in the direction of the Perseus Arm: spectral types and interstellar reddenings
• The structure of the Milky Way based on unWISE 3.4$\mu$m integrated photometry
• First results of an H-alpha based search of classical Be stars in the Perseus Arm and beyond
• Red Runaways: Hypervelocity Stars, Hills Ejecta and Other Outliers in the F-M Star Regime
• Exploring the structure and kinematics of the Milky Way through A stars
• Stellar physical parameters from Str ömgren photometry. Application to the young stars in the Galactic anticenter survey
• A and F stars as probes of outer Galactic disc kinematics
• The Milky Way thin disk structure as revealed by stars and young open clusters
• Glow in the Dark Matter: Observing galactic halos with scattered light
• The Stellar Population of the Thin Disk
• The Planck submillimeter properties of Galactic high-mass star forming regions: dust temperatures, luminosities, masses and Star Formation Efficiency
• The Sagittarius stellar stream embedded in a fermionic dark matter halo
• Molecular Gas in the Outskirts of Galaxies
• Dynamical modelling of galactic disc outskirts