J/MNRAS/325/931 Metal-poor subdwarfs in the Hipparcos catalog (Reid+, 2001)
A search for previously unrecognized metal-poor subdwarfs in the Hipparcos
astrometric catalogue.
Reid I.N., Wyk F.V., Marang F., Roberts G., Kilkenny D., Mahoney S.
<Mon. Not. R. Astron. Soc. 325, 931 (2001)>
=2001MNRAS.325..931R 2001MNRAS.325..931R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, subdwarf ; Stars, metal-deficient ; Stars, halo ;
Parallaxes, trigonometric
Keywords: stars: abundances - subdwarfs - Galaxy: halo
Abstract:
We have identified 317 stars included in the Hipparcos astrometric
catalogue that have parallaxes measured to a precision of better than
15 per cent, and the location of which in the (MV, (B-V)T) diagram
implies a metallicity comparable to or less than that of the
intermediate-abundance globular cluster M5. We have undertaken an
extensive literature search to locate Stroemgren, Johnson/Cousins and
Walraven photometry for over 120 stars. In addition, we present new
UBV(RI)C photometry of 201 of these candidate halo stars, together
with similar data for a further 14 known metal-poor subdwarfs. These
observations provide the first extensive data set of RCIC
photometry of metal-poor, main-sequence stars with well-determined
trigonometric parallaxes. Finally, we have obtained
intermediate-resolution optical spectroscopy of 175 stars. 47 stars
still lack sufficient supplementary observations for population
classification; however, we are able to estimate abundances for 270
stars, or over 80 per cent of the sample. The overwhelming majority
have near-solar abundance, with their inclusion in the present sample
stemming from errors in the colours listed in the Hipparcos catalogue.
Only 44 stars show consistent evidence of abundances below
[Fe=H]=-1.0. Nine are additions to the small sample of metal-poor
subdwarfs with accurate photometry. We consider briefly the
implication of these results for cluster main-sequence fitting
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 99 317 Candidate subdwarf sample
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP HIP number (Cat. I/239)
8- 12 F5.2 mag VT total V magnitude
14- 17 F4.2 mag (B-V)T Total B-V colour index
19- 23 F5.1 mas plx Trigonometric parallax
24- 25 A2 --- n_plx Note on plx (1)
27- 31 F5.3 --- e_plx/plx Accuracy of the parallax measurement
33- 36 F4.2 mag VMAG Absolute V magnitude
38- 42 F5.2 mag Vl HIP V magnitude
44- 47 F4.2 mag (B-V)l ? HIP B-V colour index
50- 61 A12 --- Name Other name
63- 67 A5 --- Phot [C1sOW ] Available photometry (2)
69 A1 --- Spec [Y] Y: spectroscopic observations from
Las Campanas (see Section 6 of the paper)
71- 73 A3 --- Sd? [DHI?/ ] Final abundance classification (3)
75- 99 A25 --- Com Comments (4)
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Note (1): Notes:
F: goodness-of-fit statistic, [F], listed in the Hipparcos catalogue
exceeds 2.5, and that the astrometric solution is not reliable.
*: the parallax given in the Hipparcos catalogue has been revised.
Note (2): Avaliable photometry:
s: Stroemgren
W: Walraven
O: UBV(RI) (literature)
C & C1: UBVRI (SAAO), Cl indicates single-epoch observations
Note (3): Final abundance classification:
D: [m/H]≥ -0.3
I: -0.3 > [m/H]
H: [m/H] ≤ -1
Note (4): Comments on known double stars and gives the basis for the abundance
classification:
UBV-δ0.6/[Fe/H] calibration (Section 4);
uvby-Stroemgren data (Section 3.1);
Walraven photometry (Section 3.2);
or spectroscopic measurements, referenced as follows:
AFG: Axer et al., 1994A&A...291..895A 1994A&A...291..895A
CLLA: Carney et al., 1994, Cat. J/AJ/107/2240
F20: Fulbright, 2000AJ....120.1841F 2000AJ....120.1841F
GCC: Gratton et al., 1997ApJ...491..749G 1997ApJ...491..749G
LCO: this paper
RN: Ryan & Norris, 1991AJ....101.1835R 1991AJ....101.1835R
U1: Upgren, 1972AJ.....77..486U 1972AJ.....77..486U
Stars classed as double in the Hipparcos catalogue are flagged as Dbl.
Dbl. G indicates the presence of an acceleration term in the
Hipparcos solution, interpreted as motion in an unresolved
binary system;
Dbl. C identifies separately resolved components, solutions with
quality A- D
Dbl. O indicates full orbital solutions;
Dbl. X indicates problems with both single-star and binary
Hipparcos solutions;
Dbl. S flags suspected double stars. See Hipparcos catalogue for
full details.
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History:
From electronic version of the journal
(End) Patrici Bauer [CDS] 13-Sep-2001