The Absolute Magnitude of RR Lyrae Stars Derived from the [ITAL]Hipparcos[/ITAL] Catalogue

Open Access
Publisher Website
Google Scholar
Abstract
The present determination of the absolute magnitude MV(RR) of RR Lyrae stars is twofold, relying upon Hipparcos proper motions and trigonometric parallaxes separately. First, applying the statistical parallax method to the proper motions, we find MV(RR) = 0.69±0.10 for 99 halo RR Lyrae stars with [Fe/H] = -1.58. Second, applying the Lutz-Kelker correction to the RR Lyrae HIP 95497 with the most accurately measured parallax, we obtain MV(RR) = (0.58–0.68)+0.28−0.31 at [Fe/H] = -1.6. Furthermore, allowing full use of low-accuracy and negative parallaxes, as well 125 RR Lyrae stars with -2.49 ≤ [Fe/H] ≤ 0.07, the maximum likelihood estimation yields the relation MV(RR) = (0.59 ± 0.37) + (0.20 ± 0.63)([Fe/H] + 1.60), which formally agrees with the recent preferred relation. The same estimation again yields MV(RR) = 0.65±0.33 for the 99 halo RR Lyrae stars. Although the formal errors in the latter three parallax estimates are rather large, all four results suggest the fainter absolute magnitude, MV(RR) ≈ 0.6-0.7 at [Fe/H] = -1.6. The present results still provide the lower limit on the age of the universe that is inconsistent with a flat, matter-dominated universe and current estimates of the Hubble constant.
All Related Versions