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26 April 2024 |
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The Absolute Magnitude of RRc Variables From Statistical Parallax | | Juna A. Kollmeier
; Dorota M. Szczygiel
; Christopher R. Burns
; Andrew Gould
; Ian B. Thompson
; George W. Preston
; Christopher Sneden
; Jeffrey D. Crane
; Subo Dong
; Barry F. Madore
; Nidia Morrell
; Jose L. Prieto
; Stephen Shectman
; Joshua D. Simon
; Edward Villanueva
; | | Date: |
13 Aug 2012 | | Abstract: | We present the first definitive measurement of the absolute magnitude of RR
Lyrae c-type variable stars (RRc) determined purely from statistical parallax.
We use a sample of 247 RRc selected from the All Sky Automated Survey (ASAS)
for which high-quality light curves, photometry and proper motions are
available. We obtain high-resolution echelle spectra for these objects to
determine radial velocities and abundances as part of the Carnegie RR Lyrae
Survey (CARRS). We find that M_(V,RRc) = 0.52 +/- 0.11 at a mean metallicity of
[Fe/H] = -1.59. This is to be compared with previous estimates for RRab stars
(M_(V,RRab) = 0.75 +/- 0.13 and the only direct measurement of an RRc absolute
magnitude (RZ Cephei, M_(V, RRc) = 0.27 +/- 0.17). We find the bulk velocity of
the halo to be (W_pi, W_theta, W_z) = (10.9,34.9,7.2) km/s in the radial,
rotational and vertical directions with dispersions (sigma_(W_pi),
sigma_(W_theta), sigma_(W_z)) = (154.7, 103.6, 93.8) km/s. For the disk, we
find (W_pi, W_theta, W_z) = (8.5, 213.2, -22.1) km/s with dispersions
(sigma_(W_pi), sigma_(W_theta), sigma_(W_z)) = (63.5, 49.6, 51.3) km/s.
Finally, we suggest that UCAC2 proper motion errors may be overestimated by
about 25% | | Source: | arXiv, 1208.2689 | | Services: | Forum | Review | PDF | Favorites | |
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