We determined the ages , the kinematic parameters and Galactic orbital parameters of six metal-poor ( - 2.4 < [ Fe/H ] < -1.0 dex ) F-type high proper motion ( HPM ) stars to investigate their HPM nature and origin .
For the kinematical procedure , the astrometric data from the Gaia DR2 was used .
High resolution ELODIE spectra of the six dwarfs were also used to obtain accurate [ Fe/H ] abundances and up-to-date [ \alpha /Fe ] abundances .
The calculations for stellar ages were based on Bayesian statistics , with the computed ages falling in the range 9.5-10.1 Gyrs .
On the basis of the metallicities and ages , six HMP stars are members of halo ( HD6755 , HD84937 , BD +42 3607 ) or members of the low-metallicity tail of the thick disk ( HD 3567 , HD 194598 , HD 201891 ) .
However , Galactic orbital parameters suggest thin disk ( HD 84937 , HD 194598 ) , thick disk ( HD 3567 , HD 201891 ) , and halo ( HD 6755 , BD +42 3607 ) population .
The dynamical analysis was also performed for the escape scenario from the candidate GCs .
The tidal disruption of a dwarf galaxy was also considered to be as an alternative origin .
HD 6755 , HD 194598 , and HD 3567 with their retrograde orbital motions are likely candidate stars for a tidally disrupted dwarf galaxy origin .
However , HD 194598 relationship with NGC 6284 presents an interesting case .
Its encounter velocity is low ( 16 \pm 28 km s ^ { -1 } ) and their ages and metallicities are very nearly consistent with each other at the 1 \sigma level .
The rest of the HPM sample stars have a 4 \% to 18 \% probability of encountering with selected GCs for 1.5 tidal radii .
This indicates that a globular cluster origin for the program stars is unlikely .