The Distance to the Galactic Center Derived From Infrared Photometry of Bulge Red Clump Stars

Shogo Nishiyama1, Tetsuya Nagata2, Shuji Sato1, Daisuke Kato1, Takahiro Nagayama2, Nobuhiko Kusakabe3, Noriyuki Matsunaga4, Takahiro Naoi5, Koji Sugitani6, and Motohide Tamura7


(1) Department of Astrophysics, Nagoya University, Nagoya 464-8602, Japan
(2) Department of Astronomy, Kyoto University, Kyoto 606-8502, Japan
(3) Department of Astronomical Sciences, Graduate University for Advanced Studies (Sokendai), Mitaka, Tokyo 181-8588, Japan
(4) Institute of Astronomy, School of Science, University of Tokyo, Mitaka, Tokyo, 181-0015, Japan
(5) Department of Infrared Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510, Japan
(6) Graduate School of Natural Sciences, Nagoya City University, Nagoya, 467-8501, Japan
(7) National Astronomical Observatory of Japan, Mitaka, Tokyo, 181-8588, Japan

Paper: ApJ, Aug 2006, in press

EPrint Server: astro-ph/0607408


Abstract:

On the basis of the near infrared observations of bulge red clump stars near the Galactic center, we have determined the galactocentric distance to be R0 = 7.52 +- 0.10 (stat) +- 0.35 (sys) kpc. We observed the red clump stars at |l| < 1.0 deg and 0.7 deg < |b| < 1.0 deg with the IRSF 1.4 m telescope and the SIRIUS camera in the H and Ks bands. After extinction and population corrections, we obtained (m - M)0 = 14.38 +- 0.03 (stat) +- 0.10 (sys). The statistical error is dominated by the uncertainty of the intrinsic local red clump stars' luminosity. The systematic error is estimated to be +- 0.10 including uncertainties in extinction and population correction, zero-point of photometry, and the fitting of the luminosity function of the red clump stars. Our result, R0 = 7.52 kpc, is in excellent agreement with the distance determined geometrically with the star orbiting the massive black hole in the Galactic center. The recent result based on the spatial distribution of globular clusters is also consistent with our result. In addition, our study exhibits that the distance determination to the Galactic center with the red clump stars, even if the error of the population correction is taken into account, can achieve an uncertainty of about 5 percent, which is almost the same level as that in recent geometrical determinations.


Preprints available from the authors at shogo@optik.mtk.nao.ac.jp , or the raw TeX (no figures) if you click here.

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