Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Absolute Magnitude of RR Lyrae Stars Derived from the Hipparcos
  Catalogue   The present determination of the absolute magnitude $M_V(RR)$ 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 $<M_V(RR)>=0.69\pm0.10$ for 99 halo RR Lyraes with
$<$[Fe/H]$>$ =--1.58. Second, applying the Lutz-Kelker correction to the RR
Lyrae HIP95497 with the most accurately measured parallax, we obtain
$M_V(RR)$=(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 for 125 RR Lyraes with
-- 2.49$\leq$[Fe/H]$\leq$0.07, the maximum likelihood estimation yields the
relation, $M_V(RR)$=(0.59$\pm$0.37)+(0.20$\pm$0.63)([Fe/H]+1.60), which
formally agrees with the recent preferred relation. The same estimation yields
again $<M_V(RR)>$ = $0.65\pm0.33$ for the 99 halo RR Lyraes. Although the
formal errors in the latter three parallax estimates are rather large, all of
the four results suggest the fainter absolute magnitude,
$M_V(RR)$$\approx$0.6--0.7 at [Fe/H]=--1.6. The present results still provide
the lower limit on the age of the universe which is inconsistent with a flat,
matter-dominated universe and current estimates of the Hubble constant.

16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat