NOAO >   Observing Info >   Approved Programs >   2007B-0072

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Proposal Information for 2007B-0072


PI: Tomoki Morokuma, National Astronomical Observatory of Japan, tmorokuma@ioa.s.u-tokyo.ac.jp
Address: Division of Optical and Infrared Astronomy, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan

CoI: Mamoru Doi, University of Tokyo
CoI: Naoki Yasuda, University of Tokyo
CoI: Kazuhiro Sekiguchi, National Astronomical Observatory of Japan

Title: Identifications of the Most Distant Galactic Stars

Abstract: We propose to carry out V-band imaging observations during 2 nights down to V~22.5 mag for our RR Lyrae variable star (RRL) candidates in order to determine precise periods and amplitudes of their variations. These RRL candidates have been selected by our deep optical variability survey with a wide-field camera, Suprime-Cam, on Subaru 8.2- m telescope. Over ~1 deg^2, we found many (~30) blue (B- V~0.4) variable stars including 4 good RRL candidates with large variations. However, our poor time sampling observations do not allow us to determine periods and amplitudes of their variations and to confirm that they are really RRLs. Observations proposed here provides us a sample of the most distant Galactic stars at ~100 kpc from the Galactic center as well as understanding our selection efficiency of RRLs from poor time sampling multi-epoch observations. This is the first step towards tracing the outermost Galactic structures by deep variability surveys over wide fields.


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