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 GCDistance.tex ApJ, Aug 2006, in press
From: Shogo NISHIYAMA <shogo@optik.mtk.nao.ac.jp>
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%astro-ph/0607408
\documentclass[12pt,preprint]{aastex}


\begin{document}

\title{The Distance to the Galactic Center
Derived From Infrared Photometry of Bulge Red Clump Stars}

\author{Shogo Nishiyama\altaffilmark{1}, 
Shuji Sato\altaffilmark{1},
Takahiro Nagayama\altaffilmark{2},
Noriyuki Matsunaga\altaffilmark{4}, 
Koji Sugitani\altaffilmark{6}, and
}
Nagoya 464-8602, Japan; shogo@optik.mtk.nao.ac.jp}
\altaffiltext{2}{Department of Astronomy, Kyoto University, 
Kyoto 606-8502, Japan}
\altaffiltext{3}{Department of Astronomical Sciences,
Graduate University for Advanced Studies (Sokendai),
Mitaka, Tokyo 181-8588, Japan}
\altaffiltext{4}{Institute of Astronomy, School of Science, 
University of Tokyo, Mitaka, Tokyo, 181-0015, Japan}
\altaffiltext{5}{
Department of Infrared Astrophysics,
Institute of Space and Astronautical Science,
Japan Aerospace Exploration Agency,
Sagamihara, Kanagawa 229-8510, Japan
}
\altaffiltext{6}{Graduate School of Natural Sciences, Nagoya City University,
Nagoya, 467-8501, Japan}
\altaffiltext{7}{National Astronomical Observatory of Japan, 
Mitaka, Tokyo, 181-8588, Japan}


\begin{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
R_0 = 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, R_0 = 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.
\end{abstract}

\end{document}