Stellar Absolute Magnitudes via the Statistical Parallax Method

Abstract

I review statistical parallax absolute magnitude determinations which employ data from the HIPPARCOS satellite for RR Lyrae and Cepheid variables, and for several other stellar classes. Five groups have studied the RR Lyrae stars, and the results are reassuringly consistent: M_V(RR) = 0.77 +- 0.13 mag at [Fe/H] = -1.6 dex. Extensive Monte Carlo simulations showed that systematic errors are small (~0.03 mag or less), and corrections for them were applied in the above result. The RR Lyrae result is thus very secure. A statistical parallax study of Cepheids found the Period--Luminosity zero-point to be considerably fainter than studies based on HIPPARCOS trigonometric parallaxes. The distance modulus of the Large Magellanic Cloud derived from this zero-point is in excellent agreement with that derived using the RR Lyrae result. I discuss why the statistical parallax absolute magnitude calibrations differ with some other RR Lyrae and Cepheid calibrations.