NOAO >   Observing Info >   Approved Programs >   2009A-0223

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Proposal Information for 2009A-0223


PI: Tsuyoshi Sakamoto, Japan Spaceguard Association, sakamoto@spaceguard.or.jp
Address: Bisei Spaceguard Center, 1716-3, Ookura, Bisei, Ibara, Okayama 714-1411, Japan

CoI: Takashi Hasegawa, Gunma Astronomical Observatory

Title: Stellar kinematics of Galactic disk: Short-period Mira stars

Abstract: Kinematical properties of stars in Galactic disk provide important information on its dynamical evolution and gravitational field. Previous studies of nearby stars showed the existence of some comoving groups as well as that of dynamically relaxed velocity distribution. However, the formation process of the moving groups is still less well understood because of no limits on the outer Lindblad resonance (OLR). Short-period Mira variable (SP-Miras) stars are good tracers for determination of kinematical properties because they are a very luminous and relatively old population and their periods are good distance indicators. We estimated full velocities of 58 SP-Miras at Galactocentric distance of 6-8 kpc and suggested from the systematic- velocities that the OLR appears to be located within 6 kpc from Galactic center. To set stronger limits on the OLR by the sample within 6 kpc, we propose to measure the radial velocities for 33 SP-Miras with no radial velocities at Galactocentric distance of 5-6 kpc and estimate the systematic velocity from their full space motions.


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NOAO >   Observing Info >   Approved Programs >   2009A-0223

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