The kinematics and zero-point of the log P–〈MK〉 relation for Galactic RR Lyrae variables via statistical parallaxстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:We use accurate absolute proper motions and Two-Micron All-Sky Survey Ks-band apparent magnitudes for 364 Galactic RR Lyrae variables to determine the kinematical parameters of the Galactic RR Lyrae population and constrain the zero-point of the Ks-band period-luminosity relation for these stars via statistical parallax. We find the mean velocities of the halo- and thick-disc RR Lyrae populations in the solar neighbourhood to be [U0(Halo), V0(Halo), W0(Halo)] = (-12 +/- 10, -217 +/- 9, -6 +/- 6)kms-1 and [U0(Disc), V0(Disc), W0(Disc)] = (-15 +/- 7, -44 +/- 7, -25 +/- 5)kms-1, respectively, and the corresponding components of the velocity-dispersion ellipsoids, [σVR(Halo), σVθ(Halo), σW(Halo)] = (167 +/- 9, 86 +/- 6, 78 +/- 5)kms-1 and [σVR(Disc), σVθ(Disc), σW(Disc)] = (55 +/- 7, 44 +/- 6, 30 +/- 4)kms-1, respectively. The fraction of thick-disc stars is estimated at 0.25 +/- 0.03. The corrected infrared period-luminosity relation is , implying a Large Magellanic Cloud (LMC) distance modulus of 18.27 +/- 0.08 and a solar Galactocentric distance of 7.58 +/- 0.40 kpc. Our results suggest no or slightly prograde rotation for the population of halo RR Lyraes in the Milky Way.