The distance to the galactic center derived from infrared photometry of bulge red clump stars

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 vertical bar l vertical bar less than or similar to 1.degrees 0 and 0.degrees 7 less than or similar to vertical bar b vertical bar less than or similar to 1.degrees 0 with the IRSF 1.4 m telescope and the SIRIUS camera in the H and K-S 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%, which is almost the same level as that in recent geometrical determinations.