2.3.3. Red Clump

The OGLE group revived the use of the red clump (He burning stage of Population I stars) as a distance indicator. Paczynski & Stanek (1998) showed that the I band luminosity of the red clumps depends little on metallicity (see, Cole 1998, however), and gave a calibration using the Hipparcos parallax for nearby He burning stars. Udalski et al. (1998a) and Stanek et al. (1998) applied this to LMC, and obtained a distance modulus 18.1 ± 0.1, much shorter than those from other methods. This is a modern version of an analysis of Mateo & Hodge (1986), who reported 18.1 ± 0.3. We should also recall that earlier analyses using MS fitting of OB stars resulted in a short distance of 18.2-18.3 (Schommer et al. 1984; Conti et al. 1986), though somewhat dismissed in the modern literature.