Yazar "Seabroke, G. M." seçeneğine göre listele

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    Identification of field dwarfs and giants in the second Radial Velocity Experiment Data Release
    (Wiley-Blackwell, 2011) Bilir, S.; Karaali, S.; Ak, S.; Onal, O.; Coskunoglu, B.; Seabroke, G. M.
    The second Radial Velocity Experiment (RAVE) Data Release (DR2) derives log g values. However, we present a simpler and cleaner method of identifying dwarfs and giants by using only magnitudes, which does not require spectroscopic analysis. We confirm the method presented in an earlier paper, with which we estimate the number of dwarfs and giants using their positions in the JV two-magnitude diagram, by applying it to RAVE DR2. It is effective in estimating the number of dwarfs and giants at JH > 0.4 compared to RAVEs log g values. For JH= 0.4, where dwarfs and subgiants show a continuous transition in the J magnitude histogram, we used the Besancon Galaxy model predictions to statistically isolate giants. The percentages of giants for red stars and for the whole sample are 85 and 34 per cent, respectively. If we add the subgiants, the percentage of evolved stars for the whole sample increases to 59 per cent. For the first time in the literature, we have analysed the effect of CHISQ on RAVEs log g values (CHISQ is the penalized 2 from RAVEs technique of finding an optimal match between the observed spectrum and synthetic spectra to derive stellar parameters). Neither the CHISQ values nor the signal-to-noise ratio bias the RAVE log g values. Therefore, the method of identifying dwarfs and giants using the two-magnitude diagram has been verified against an unbiased data set.
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    Local stellar kinematics from RAVE data - I. Local standard of rest
    (Oxford Univ Press, 2011) Coskunoglu, B.; Ak, S.; Bilir, S.; Karaali, S.; Yaz, E.; Gilmore, G.; Seabroke, G. M.
    We analyse a sample of 82 850 stars from the RAdial Velocity Experiment (RAVE) survey, with well-determined velocities and stellar parameters, to isolate a sample of 18 026 high-probability thin-disc dwarfs within 600 pc of the Sun. We derive space motions for these stars, and deduce the solar space velocity with respect to the local standard of rest. The peculiar solar motion we derive is in excellent agreement in radial U-circle dot and vertical W-circle dot peculiar motions with other recent determinations. Our derived tangential peculiar velocity, V-circle dot, agrees with very recent determinations, which favour values near 13 km s-1, in disagreement with earlier studies. The derived values are not significantly dependent on the comparison sample chosen, or on the method of analysis. The local Galaxy seems very well dynamically relaxed, in a near symmetric potential.