ar X iv : a st ro - p h / 98 02 12 1 v 2 1 1 Fe b 19 98 Distance to M 31 With the HST and Hipparcos Red Clump Stars

Following an approach by Paczy´nski & Stanek we compare red clump stars with parallaxes known to better than 10% in the Hipparcos catalog with the red clump stars observed in three fields in M31 using the HST. There are ∼ 600 and ∼ 6, 300 such stars in the two data sets, respectively. The local red clump luminosity function is well represented by a Gaussian with the peak at M I 0 ,m = −0.23, and the dispersion σ RC ≈ 0.2 mag. This allows a single step determination of the distance modulus to M31