On the Oosterhoff dichotomy in the Galactic bulge: II. kinematical distribution. (arXiv:1905.11870v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Prudil_Z/0/1/0/all/0/1">Z. Prudil</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dekany_I/0/1/0/all/0/1">I. Dékány</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grebel_E/0/1/0/all/0/1">E. K. Grebel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Catelan_M/0/1/0/all/0/1">M. Catelan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Skarka_M/0/1/0/all/0/1">M. Skarka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smolec_R/0/1/0/all/0/1">R. Smolec</a>
We present a kinematical study of RR~Lyrae stars associated with two
Oosterhoff groups in the Galactic bulge. We used data published in the first
paper of the series, plus proper motions from the {it Gaia} Data Release 2,
and radial velocities from the literature. A 6D kinematical and spatial
solution was obtained for 429 RR~Lyrae stars. We use a model of the Galactic
gravitational potential to infer stellar orbits. We did not find a difference
between the Oosterhoff groups in the individual components of the space
velocity. We report that textit{foreground} and textit{background} stars with
respect to the Galactic bulge stand out in the mean $V$ velocity component,
which we interpret as a sign of the Galactic rotation. The movement of the
studied stars in the central region of the Galactic bulge is consistent with
random motions expected for a classical bulge component. From the orbital
integration, we estimate that 8,% of the RR~Lyrae stars are halo interlopers
currently located in the Galactic bulge. The majority of the stars’ orbits are
within a 3,kpc radius from the Galactic bulge. The fraction of Oosterhoff,II
stars increases with increasing Galactic latitude, as well as towards longer
orbital periods. We found several RR~Lyrae stars with high space velocities,
one of which has an extremely long orbital period of $sim$1,Gyr. We conclude
that based on their kinematics, the vast majority of the stars in our sample do
not seem to contribute to the boxy/peanut component of the Galactic bulge.
We present a kinematical study of RR~Lyrae stars associated with two
Oosterhoff groups in the Galactic bulge. We used data published in the first
paper of the series, plus proper motions from the {it Gaia} Data Release 2,
and radial velocities from the literature. A 6D kinematical and spatial
solution was obtained for 429 RR~Lyrae stars. We use a model of the Galactic
gravitational potential to infer stellar orbits. We did not find a difference
between the Oosterhoff groups in the individual components of the space
velocity. We report that textit{foreground} and textit{background} stars with
respect to the Galactic bulge stand out in the mean $V$ velocity component,
which we interpret as a sign of the Galactic rotation. The movement of the
studied stars in the central region of the Galactic bulge is consistent with
random motions expected for a classical bulge component. From the orbital
integration, we estimate that 8,% of the RR~Lyrae stars are halo interlopers
currently located in the Galactic bulge. The majority of the stars’ orbits are
within a 3,kpc radius from the Galactic bulge. The fraction of Oosterhoff,II
stars increases with increasing Galactic latitude, as well as towards longer
orbital periods. We found several RR~Lyrae stars with high space velocities,
one of which has an extremely long orbital period of $sim$1,Gyr. We conclude
that based on their kinematics, the vast majority of the stars in our sample do
not seem to contribute to the boxy/peanut component of the Galactic bulge.
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