J/A+AS/117/317 uvby-beta photometry of metal-poor stars. VIII. (Schuster+ 1996)
uvby-β photometry of high-velocity and metal-poor stars.
VIII. Stars of very low metal abundance.
Schuster W.J., Nissen P.E., Parrao L., Beers T.C., Overgaard L.P.
<Astron. Astrophys. Suppl. Ser. 117, 317 (1996)>
=1996A&AS..117..317S 1996A&AS..117..317S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, high-velocity ; Stars, metal-deficient ;
Photometry, uvby, beta ; Abundances, [Fe/H]
Keywords: stars: abundances - stars: distances - stars: fundamental parameters -
dust, extinction - Galaxy: evolution - Galaxy: halo
Abstract:
A catalogue of uvby-β photometry for 87 of the turn-off and
subgiant stars from the HK survey of Beers et al.
(1992AJ....103.1987B 1992AJ....103.1987B, BPSII) is given. Most of these stars have
[Fe/H]≤2.5. These photometric data have been taken and reduced using
the same techniques as in our previous two uvby-β catalogues
(Schuster et al., 1989, Cat. II/180 and Schuster et al., 1993, Cat.
J/A+AS/97/951). An error analysis has been made; typical mean
observational errors for a star with V=14.2m are 0.008, 0.007, 0.011,
0.010 and 0.012 in V, (b-y), m1, c1 and β, respectively. Our
photometric data are also compared to the UBV photometry and spectral
indices from the HK survey; satisfactory agreement is found indicating
good quality for the two data sets. The stars are classified in
reddening-free diagrams of the uvby-β system; several of the
stars are found to have been mis-classified in the HK survey. Two
metal-poor supergiants, three (possibly four) horizontal branch stars,
one blue subluminous star and two stars with ambiguous photometry have
been identified. Stellar parameters, such as E(b-y), MV,
δMV, and Teff, plus error estimates for these parameters,
are provided using our photometric calibrations. Although all stars
have galactic latitudes |b|≥30° many of them are significantly
reddened with E(b-y) ranging from 0.02 to 0.15. The average reddening
towards the South Galactic Pole region, b←60°, is
E(b-y)=0.027±0.004 corresponding to E(B-V)=0.036±0.005 in contrast
to the low value of E(B-V)∼0.01 derived from the Burstein & Heiles
(1982AJ.....87.1165B 1982AJ.....87.1165B) maps. The stars are analyzed in the (b-y)0,
[Fe/H] diagram, and individual ages estimated using the isochrones of
VandenBerg & Bell (1985ApJS...58..561V 1985ApJS...58..561V) and of Bergbusch & VandenBerg
(1992ApJS...81..163B 1992ApJS...81..163B). These very metal-poor stars are found to be
coeval, within 1-2Gyr, with the halo and thick-disk stars studied
previously, with a mean age in excess of 18Gyr. Several blue
"thick-disk" stars, which are perhaps analogous to the "blue
metal-poor" stars of Preston et al. (1994, Cat. J/AJ/108/538), have
been identified.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1 80 87 The standard uvby-β catalogue for the 87 BPSII
(Beers et al., 1992AJ....103.1987B 1992AJ....103.1987B) stars
table2 70 86 Stellar parameters for the 86 VMP stars.
--------------------------------------------------------------------------------
See also:
II/180 : uvby-beta photometry of metal-poor stars. III. (Schuster+ 1989)
J/A+AS/97/951 : uvby-beta photometry of metal-poor stars. VI. (Schuster+ 1993)
J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992)
J/A+A/422/527 : Metal-poor stars uvby-beta photometry. X. (Schuster+, 2004)
J/A+A/445/939 : Metal-poor stars uvby-beta photometry. XI. (Schuster+, 2006)
Byte-by-byte Description of file: table1
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Star Star designation according to BPSII
(Beers et al., 1992AJ....103.1987B 1992AJ....103.1987B)
11- 16 F6.3 mag Vmag V magnitude
18- 22 F5.3 mag b-y b-y colour index
24- 29 F6.3 mag m1 m1 colour index
31- 35 F5.3 mag c1 c1 colour index
37 I1 --- o_b-y Number of independent uvby observations
39- 43 F5.3 mag beta beta colour index
45 I1 --- o_beta Number of independent beta observations
47- 80 A34 --- Note Note
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Star Star designation according to BPSII
(Beers et al., 1992AJ....103.1987B 1992AJ....103.1987B)
11- 16 F6.3 mag E(b-y) ? Reddening
18- 22 F5.3 mag e_E(b-y) ? rms uncertainty on E(b-y)
24- 28 F5.2 [Sun] [Fe/H]c ? Spectroscopic metallicity
30- 34 F5.2 [Sun] [Fe/H]p ? Photometric metallicity
35 A1 --- u_[Fe/H]p Uncertainty flag on [Fe/H]p
37- 40 F4.2 [Sun] e_[Fe/H]p ? rms uncertainty on [Fe/H]p
42- 45 F4.2 mag MV ? Absolute V magnitude
47- 50 F4.2 mag e_MV ? rms uncertainty on MV
52- 56 F5.2 mag dMV ? Evolutionnary correction δMV
(See Nissen et al., 1991A&A...251..457N 1991A&A...251..457N)
58- 61 F4.2 mag e_dMV ? rms uncertainty on dMV
63- 66 I4 K Teff ? Effective temperature
68- 70 I3 K e_Teff ? rms uncertainty on Teff
--------------------------------------------------------------------------------
History: Prepared via OCR at CDS.
References:
Schuster at al., Paper I. 1988A&AS...73..225S 1988A&AS...73..225S
Schuster at al., Paper II. 1989A&A...221...65S 1989A&A...221...65S
Schuster at al., Paper III. 1989A&A...222...69S 1989A&A...222...69S, Cat. II/180
Allen et al., Paper IV. 1991A&A...244..280A 1991A&A...244..280A
Nissen et al., Paper V. 1991A&A...251..457N 1991A&A...251..457N
Schuster et al. Paper VI. 1993A&AS...97..951S 1993A&AS...97..951S, Cat. J/A+AS/97/951
Marquez et al., Paper VII. 1994A&AS..108..341M 1994A&AS..108..341M
Schuster at al., Paper IX. 1997A&A...319..796S 1997A&A...319..796S
Schuster at al., Paper X. 2004A&A...422..527S 2004A&A...422..527S, Cat. J/A+A/422/527
Schuster at al., Paper XI. 2006A&A...445..939S 2006A&A...445..939S, Cat. J/A+A/445/939
(End) James Marcout, Patricia Bauer [CDS] 12-Sep-1997