Galactic structure studies from BATC survey

Abstract

We present an analysis of the photometric parallaxes of stars in 21 BATC fields carried out with the National Astronomical Observatories (NAOC) 60/90 cm Schmidt Telescope in 15 intermediate-band filters from 3000 to 10000 Å. In this study, we have adopted a three-component (thin disk, thick disk and halo) model to analyze star counts information. By calculating the stellar space density as a function of distance from the Galactic plane, we determine that the range of scale height for the thin disk varies from 220 to 320 pc. Although 220 pc seems an extreme value, it is close to the lower limit in the literature. The range of scale height for the thick disk is from 600 to 1100 pc, and the corresponding space number density normalization is 7.0-1.0% of the thin disk. We find that the scale height of the disk may be variable with observed direction, which cannot simply be attributed to statistical errors. Possibly the main reasons can be attributed to the disk (mainly the thick disk) is flared, with a scale height increasing with radius. The structure is consistent with merger origin for the thick disk formation. Adopting a de Vaucouleurs $r^{1/4}$ law halo, we also find that the axis ratio towards the Galactic center is somewhat flatter ($\sim 0.4$), while the shape of the halo in the anticentre and antirotation direction is rounder with $c/a>0.4$. Our results show that star counts in different lines of sight can be used directly to obtain a rough estimate of the shape of the stellar halo. Our solutions support the Galactic models with a flattened inner halo, possibly it is formed by a merger early in the Galaxy's history.

12 pages, 8 figure, accepted for publication in MNRAS

References in corpus (7)

• The Field of Streams: Sagittarius and its Siblings
• The Emergence of the Thick Disk in a CDM Universe II: Colors and Abundance Patterns
• A different approach for the estimation of Galactic model parameters
• The investigation of ELAIS field by Vega photometry: Absolute - magnitude dependent on the Galactic model parameters
• Kinematics of RHB stars to trace the structure of the galaxy
• The metallicity distribution of F/G dwarfs derived from BATC survey data
• The asymmetric structure of the Galactic halo

Cited by in corpus (22)

• Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
• Constraining the thick disc formation scenario of the Milky Way
• Kinematical and chemical vertical structure of the Galactic thick disk II. A lack of dark matter in the solar neighborhood
• Cataclysmic Variables from the Catalina Real-time Transient Survey
• Stellar mass distribution and star formation history of the Galactic disk revealed by mono-age stellar populations from LAMOST
• The Century Survey Galactic Halo Project III: A Complete 4300 deg^2 Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo
• Estimation of galactic model parameters in high latitudes with SDSS
• The Information Of The Milky Way From 2MASS Whole Sky Star Count: The Structure Parameters
• Chemical and Kinematic Properties of the Galactic Disk from the LAMOST and Gaia Sample Stars
• On the 3 dimensional structure of edge-on disk galaxies
• Constraining the Galactic structure parameters with the XSTPS-GAC and SDSS photometric surveys
• Estimation of Galactic Model Parameters and Metalicity Distribution in Intermediate Latitudes with SDSS
• GARROTXA Cosmological Simulations of Milky Way-sized Galaxies: General Properties, Hot Gas Distribution, and Missing Baryons
• Estimation of Absolute Magnitude-dependent Galactic Model Parameters In Intermediate Latitude With SDSS and SCUSS
• The stellar metallicity distribution in intermediate latitude fields with BATC and SDSS data
• Estimation of Galactic model parameters with the SDSS and metallicity distribution in two fields in the anti-centre direction of the Galaxy
• The stellar metallicity distribution of the Milky Way from the BATC survey
• Kinematics of the Galactic disk from LAMOST Dwarf sample
• Luminosity-Colour Relations for Red Clump Stars
• Solar Space Density of the Red Clump Stars and the Scale-length of the Thin Disc
• Galactic Stellar Populations from Photometric Metallicity Distribution Functions
• The Debris Disk Candidates: Eleven 24$\mu$m excess stars in Spitzer SWIRE Fields