III/176 RR Lyrae Metallicities (Layden 1994)
RR Lyrae data II. The Metallicities and Kinematics of Local RR Lyrae
Layden A.C.
<Astron. J. 110, 2288 (1995)>
=1995AJ....110.2288L 1995AJ....110.2288L
ADC_Keywords: Abundances ; Radial velocities ; Stars, variable ;
Stars, population II ; Abundances, [Fe/H]
Abstract:
This catalog presents metal abundance, distance and radial velocity
data on a sample of 302 ab-type RR Lyrae variables within about 2.5
kpc of the Sun. The metal abundance information was obtained from
low-medium resolution spectra, using the pseudo-equivalent widths of
the Ca II K line and the the H-delta, H-gamma and H-beta lines. The
technique employed was similar to Preston's (1959ApJ...130..507P 1959ApJ...130..507P)
Δ-S method, though significant differences exist; see the source
reference for details. The data were calibrated to the Zinn & West
(1984ApJS...55...45Z 1984ApJS...55...45Z) globular cluster abundance scale.
The photometry employed in the distance determinations was primarily
taken from the General Catalog of Variable Stars (1985, hereafter
GCVS4). Exceptions are noted in column 29; the letters match the
footnotes in Table 10 of Layden (1994AJ....108.1016L 1994AJ....108.1016L). The minimum and
maximum light photometry, and rise-time were combined following Barnes
& Hawley (1986ApJ...307L...9B 1986ApJ...307L...9B) to give an estimate of the intensity-
averaged magnitude, i.e. the magnitude the star would have if it were
not variable. When the GCVS4 quoted magnitudes in passbands other than
V, the GCVS4 magnitudes were transformed to the V passband using the
relations established in Layden (1994AJ....108.1016L 1994AJ....108.1016L). The
interstellar absorption estimates are from Burstein & Heiles
(1982AJ.....87.1165B 1982AJ.....87.1165B), modified by a simple dust-distribution model.
The distances were computed assuming the Mv(RR)-[Fe/H] relation of
Carney, Storm & Jones (1992ApJ...386..663C 1992ApJ...386..663C).
Radial velocities were measured from the spectra via cross-correlation
with secondary velocity standards. The velocities from the individual
spectra were fit with a standard radial velocity curve in the (phase,
velocity) plane, to give an estimate of the systemic (center of mass)
velocity of each star. The error in this value was estimated from the
scatter about the best-fit velocity curve, and the quality of the
spectra employed. Other methods were used to combine the individual
velocities when the situation demanded (cm = 2,3 in column 70; see
Layden (1994AJ....108.1016L 1994AJ....108.1016L) for details). The observed velocities
were combined with values from the literature to produce a final, best
estimate of the systemic radial velocity of each star, and its error.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 79 302 Data for RR Lyrae stars
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Variable star name (as in GCVS4)
10- 14 F5.2 [Sun] Fe/H *Metal abundance [Fe/H]
15 A1 --- u_Fe/H Uncertainty flag (:)
17- 20 F4.2 [Sun] e_Fe/H Estimated error in [Fe/H]
22 I1 --- o_Fe/H Number of spectra used for [Fe/H] estimate
24- 28 F5.2 mag mag Intensity-averaged magnitude (B or V)
29 A1 --- r_mag Reference of magnitude (see source reference)
31 A1 --- n_mag [BVpv] band (p=photographic, v=photovisual)
33- 36 F4.2 mag abs *Interstellar absorption in V
38- 41 F4.2 kpc dist Distance from Sun
43- 46 F4.2 kpc e_dist Estimated error in distance
48- 52 F5.2 kpc Zpos Distance from the Galactic plane
54- 58 F5.2 kpc Rpos Distance from the Galactic center
60- 63 I4 km/s RVm Measured systemic radial velocity
65- 66 I2 km/s e_RVm Estimated error in measured radial velocity
67- 68 I2 --- o_RVm Number of spectra used for radial velocity
70 I1 --- n_RVf *[1,3] Radial velocity combination method
72- 75 I4 km/s RVf *Final systemic radial velocity
77- 78 I2 km/s e_RVf Estimated error in final radial velocity
79 A1 --- u_RVf *Measured and published disagreement
--------------------------------------------------------------------------------
Note on Fe/H:
On the Zinn & West scale (1984ApJS...55...45Z 1984ApJS...55...45Z)
Note on abs:
From Burstein & Heiles (1982AJ.....87.1165B 1982AJ.....87.1165B)
Note on RVf:
A combination of RVm, and values from the literature
Note on u_RVf:
A colon indicates the measured and literature velocity estimates
disagree by more than the quoted error (e_RVf). The quoted error
may be too small.
Note on n_RVf:
See section 3.13 of paper I(1994AJ....108.1016L 1994AJ....108.1016L):
1 indicates a systemic velocity from fitted radial veolcity curve;
2 indicates that several spectra of the star were used;
3 indicates that only one spectrum was available for that star.
--------------------------------------------------------------------------------
History:
* 02-May-1994: Prepared and documented by Nancy G. Roman [NASA/NSSDC/ADC]
and A. C. Layden
* 18-Oct-2008: standardized this ReadMe file (CDS)
References:
Barnes, T.G.III & Hawley, S. 1986ApJ...307L...9B 1986ApJ...307L...9B
Burstein, D. & Heiles, C. 1982AJ.....87.1165B 1982AJ.....87.1165B
Carney, B.W. Storm, J. & Jones, R.V. 1992ApJ...386..663C 1992ApJ...386..663C
Kholopov, P.N. 1985, General Catalog of Variable Stars, 4th Edition,
(Moscow: Nauka Publishing House)
Preston, G.W. 1959ApJ...130..507P 1959ApJ...130..507P
Zinn, R.J. & West, M.J. 1984ApJS...55...45Z 1984ApJS...55...45Z
(End) Nancy G. Roman [NASA/NSSDC/ADC] and A.C. Layden 02-May-1994