RR Lyrae star distance scale and kinematics from inner bulge to 50 kpc

E-ISSN： 2100-014x|152|issue|02007-02007

ISSN： 2100-014x

Source： EPJ Web of Conference, Vol.152, Iss.issue, 2017-09, pp. : 02007-02007

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Abstract

We use the currently most complete sample of ∼ 3500 type ab RR Lyraes in our Galaxy with available radial-velocity and [Fe/H] measurements to perform a statisticalparallax analysis for a subsample of ∼ 600 type ab RR Lyraes located within 5 kpc from the Sun to refine the parameters of optical and WISE W1-band period-metallicityluminosity relations and adjust our preliminary distances. The new zero point implies the rescaled estimates for the solar Galactocentric distance (R_G = 7.99 ± 0.37 kpc) and the LMC distance modulus (DM_LMC = 18.39 ±0.09). We use the kinematic data for the entire sample to explore the dependence of the halo and thick-disk RR Lyrae velocity ellipsoids on Galactocentric distance from the inner bulge out to R ∼ 50 kpc.