SIMBAD references

2009AJ....137.3198K - Astron. J., 137, 3198-3209 (2009/February-0)

Do the nearby blue horizontal branch stars belong to the thick disk or the halo?


Abstract (from CDS):

We study the Milky Way region (|Z|< 3.0 kpc) where the thick disk and inner halo overlap by using the kinematics of local blue horizontal branch (BHB) stars (within 1 kpc) and new samples of BHB stars and A-type stars from the Century Survey. We derive Galactic U, V, and W velocities for these BHB and A-type star samples using proper motions from the NOMAD catalog. The mean velocities and the velocity dispersions of the BHB samples (|Z| < 3 kpc) are characteristic of the halo, while those of the Century Survey A-type stars are characteristic of the thick disk. There is no evidence from our samples that the BHB stars rotate with the thick disk in the region|Z| < 3 kpc. Nearly a third of the nearby local RR Lyrae stars have disk kinematics and are more metal rich than [Fe/H] ∼ -1. Only a few percent of the Century Survey BHB (CBHB) stars have these properties. Only one nearby BHB star (HD 130201) is likely to be such a disk star but selection based on high proper motions will have tended to exclude such stars from the local sample. The scale height derived from a sample of local RR Lyrae stars agrees with that of the CBHB stars. The local samples of BHB stars and metal-weak red giants are too incomplete for a similar comparison.

Abstract Copyright:

Journal keyword(s): Galaxy: halo - Galaxy: structure - stars: horizontal-branch

VizieR on-line data: <Available at CDS (J/AJ/137/3198): table2.dat table3.dat>

Simbad objects: 173

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