EPJ Web of Conferences 152, 02007 (2017)
https://doi.org/10.1051/epjconf/201715202007

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

¹ Sternberg Astronomical Institute, M.V.Lomonosov Moscow State University, Universitetskii pr. 13, Moscow, 119992 Russia
² Astronomy and Astrophysics Research division, Entoto Observatory and Research Center, P.O. Box 8412, Addis Ababa, Ethiopia
³ Astronomisches Rechen-Institut Zentrum für Astronomie der Universität Heidelberg, Germany
⁴ South African Astronomical Observatory, P.O. Box 9, Observatory, Cape Town, 7935, South Africa
⁵ Southern African Large Telescope, P.O. Box 9, Observatory, Cape Town, 7935, South Africa
⁶ Special Astrophysical Observatory of RAS, Nizhnij Arkhyz, Karachai-Circassia 369167, Russia

^* dambis@yandex.ru
^** lberdnikov@yandex.ru
^*** grebel@ari.uni-heidelberg.de
^**** akniazev@saao.ac.za
^† katkov.ivan@gmail.com
^‡ tesfayedagne7@gmail.com

Published online: 8 September 2017

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.