Optical Gravitational Lensing Experiment. Distance to the Magellanic Clouds with the Red Clump Stars: Are the Magellanic Clouds 15% Closer than Generally Accepted?
We present a new distance determination to the Large and Small Magellanic Clouds using the newly developed red clump stars method (Paczynski and Stanek 1998). This new, single-step, Hipparcos calibrated method seems to be one of the most precise techniques of distance determination with very small statistical error due to large number of red clump stars usually available. The distances were determined independently along four lines-of-sight located at opposite sides of each Magellanic Cloud. The results for each line-of-sight are very consistent. For the SMC we obtain the distance modulus: m-M=18.56+/-0.03+/-0.06 mag (statistical and systematic errors, respectively) and for the LMC: m-M=18.08+/-0.03+/-0.12 mag where systematic errors are mostly due to uncertainty in reddening estimates. Both distances will be refined and systematic errors reduced when accurate reddening maps for our fields are available. Distance moduli to both Magellanic Clouds are approx 0.4 mag smaller than generally accepted values. The modulus to the LMC is in good agreement withthe recent determinations from RR Lyrae type stars and upper limit resulting from the SN1987A echo. We suspect that the distance to the LMC and SMC is shorter by about 15% than previously assumed: 42 kpc and 52 kpc, respectively. Calibrations of the period-luminosity relation for Cepheids which give overestimated distances to the LMC and SMC are probably incorrect and require urgent reanalysis. We also present our color-magnitude diagrams around the red clump for the LMC and SMC. We identify vertical red clump, first noted by Zaritsky and Lin (1997),in the color-magnitude diagram of both Magellanic Clouds and we interpret it as an evolutionary feature rather than unknown stellar population between the LMC and our Galaxy.
- Pub Date:
- January 1998
- MAGELLANIC CLOUDS;
- GALAXIES: DISTANCES AND REDSHIFTS;
- HERTZSPRUNG-RUSSEL (HR) DIAGRAM;
- 16 pages, Latex, 5 Figures (Fig.2 and 3 - jpg images). Revised version, accepted for publication in Acta Astronomica Vol. 48