Metallicity and Kinematic distributions of Red Horizontal-Branch Stars from the SDSS Survey

Abstract

On the basis of a recently derived color-metallicity relation and stellar parameters from the Sloan Digtal Sky Survey Data Release 7 spectroscopic survey, a large sample of red horizontal branch candidates have been selected to serve as standard candles. The metallicity and kinematic distributions of these stars indicate that they mainly originate from the thick-disk and the halo populations. The typical thick disk is characterized by the first group peaking at [Fe/H] ~ -0.6, Vrot ~ 170 km/s with a vertical scale height around |Z| ~ 1.2 kpc, while stars with [Fe/H] < -0.9 are dominated by the halo population. Two sub-populations of the halo are suggested by the RHB stars peaking at [Fe/H] ~-1.3: one component with Vrot > 0 km/s (Halo I) shows a sign of metallicity gradient in the [Fe/H] versus |Z| diagram, while the other with Vrot < 0 km/s (Halo II) does not. The Halo I mainly clumps at the inner halo with R < 10 kpc and the Halo II comes both from the inner halo with R < 10 kpc and the outer halo with R > 10 kpc based on the star distribution in the R versus |Z| diagram.

10 pages, 15 figures

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Cited by in corpus (6)

• On Rings and Streams in the Galactic Anti-Center
• The Metallicity Gradient of the Thick Disk Based on Red Horizontal Branch Stars From SDSS DR8
• The Kinematics and Chemistry of Red Horizontal Branch Stars in the Sagittarius Streams
• Metallicity and Kinematics of the Galactic halo from the LAMOST sample stars
• Red Horizontal Branch stars: an asteroseismic perspective
• A Spectroscopic Survey of Field Red Horizontal-Branch Stars