Access to Astronomical Catalogues

← Click to display the menu
J/AJ/108/1016      Kinematics of local RR lyrae stars. I. (Layden, 1994)

The metallicities and kinematics of RR Lyrae variables. I. New observations of local stars Layden A.C. <Astron. J. 108, 1016 (1994)> =1994AJ....108.1016L (SIMBAD/NED Reference)
ADC_Keywords: Stars, variable ; Photometry ; Abundances, [Fe/H] ; Radial velocities Abstract: In order to study the structure and formation history of the galaxy, we have obtained low-to-moderate dispersion spectra of 302 nearby RR Lyrae variables of Bailey type "ab". We derived abundances, typically accurate to 0.15-0.20dex and calibrated to the Zinn & West (1984ApJS...55...45Z) globular cluster metallicity scale, from the pseudo-equivalent widths of the Ca II K, Hdelta, Hgamma, and Hbeta lines. Radial velocities accurate to between 2 and 30km/s were obtained from the spectra and from the literature. Distances accurate to between 5% and 20% were derived from published apparent magnitudes and Burstein & Heiles (1982AJ.....87.1165B) reddenings. The metallicity distribution of the RR Lyrae stars peaks at [Fe/H]K ≃ -1.5, and is narrower than that of the Ryan & Norris (1991AJ....101.1865R) subdwarfs, as expected since the most metal-rich and metal-poor progenitors preferentially appear as stable red and blue horizontal branch stars, rather than as RR Lyrae. The metal-rich tail of the RR Lyrae distribution extends to [Fe/H]K~0, and a qualitative analysis of the distribution of distances from the galactic plane shows that the stars in this tail (i.e., [Fe/H]K>-1.0) are more concentrated to the plane than the more metal-poor stars. The abundance distribution of the local RR Lyrae stars is in excellent agreement with the changing abundance distributions of distant RR Lyrae stars as a function of galactocentric distance, as derived by Suntzeff et al. (1991ApJ...367..528S), who ascribed this change to systematic variations in horizontal branch morphology (probably age variations) with galactocentric distance. The abundance distribution of the local RR Lyrae stars also agrees well with those of the distant RR Lyrae stars as a function of distance from the galactic plane. There is no evidence for an abundance gradient in this direction, suggesting that gaseous dissipation did not play a major role in the formation of the outer halo. Addresses: Layden A.C. Department of Astronomy, Yale University, P.O. Box 208101 New Haven, Connecticut 06520-8101 File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table9.dat 79 302 New data for local RR Lyrae variables
See also: J/AJ/110/2288 : Kinematics of local RR Lyrae. II. (Layden 1995) Byte-by-byte Description of file: table9.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Variable star name (as in GCVS4, II/139) 10- 14 F5.2 [Sun] [Fe/H] Metal abundance, on Zinn & West (1984ApJS...55...45Z) scale 15 A1 --- u_[Fe/H] Uncertainty flag on [Fe/H] 17- 20 F4.2 [Sun] e_[Fe/H] rms uncertainty on [Fe/H] 22 I1 --- o_[Fe/H] Number of spectra used for [Fe/H] estimate 24- 28 F5.2 mag <V> Intensity-averaged V magnitude (see n_<V>) 29 A1 --- r_<V> Reference for <V> (see n_<V>) (1) 31 A1 --- n_<V> Photometric passband (2) 33- 36 F4.2 --- AV Interstellar absorption in V (3) 38- 41 F4.2 kpc Dist Distance from Sun 43- 46 F4.2 kpc e_Dist rms uncertainty on distance 48- 52 F5.2 kpc Z Distance from Galactic plane 54- 58 F5.2 kpc Rgc Distance from Galactic center, assumes Ro=8kpc 60- 63 I4 km/s RV Systemic radial velocity 65- 66 I2 km/s e_RV Estimated error in measured radial velocity 67- 68 I2 --- o_RV Number of spectra used in Vrad estimate 70 I1 --- Method Radial velocity combination method (4) 72- 75 I4 km/s Vsys Final systemic radial velocity (5) 77- 78 I2 km/s e_Vsys Estimated error in Vsys 79 A1 --- u_Vsys ':' indicates disagreement in velocity (6)
Note (1): Intensity-averaged V magnitude reference: a = <V> value from Schmidt 1991AJ....102.1766S b = Layden (1993, Ph.D. dissertation, Yale University) photoelectric photometry c = Layden (1993, Ph.D. dissertation, Yale University) recalibration of photographic photometry d = Photometry from Nikolev et al. 1984, The Mean Light and Colour (B-V and U-B) Curves of 210 Field RR Lyrae Types Stars, (University of Sofia, Sofia) e = GCVS4 II/139 photometry uncertain Note (2): Photometry passband: V = photoelectric V B = photoelectric B p = photographic v = (photo)visual Note (3): Interstellar absorption in V, from Burstein & Heiles 1982AJ....187.1165B Note (4): Radial velocity combination method: 1 = fits with standard RV curve 2 = weighted mean 3 = single observation only Note (5): Final systemic radial velocity, a combination of Vrad and values from the literature Note (6): A colon, ':', indicates the measured and literature velocity estimates disagree by more than the quoted error; the quoted error may be too small.
Origin: AAS CD-ROM series, Volume 3, 1995
(End) Lee Brotzman [ADS] 31-Oct-1994, Patricia Bauer [CDS] 16-Feb-1995
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

catalogue service

© UDS/CNRS

Contact