A search for previously unrecognised metal-poor subdwarfs in the Hipparcos astrometric catalogue

Abstract

We have identified 317 stars included in the Hipparcos astrometric catalogue which have parallaxes measured to a precision of better than 15%, and whose location in the (M_V, (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 Stromgren, Johnson/Cousins and Walraven photometry for over 120 stars. In addition, we present new UBVRI photometry of 201 of these candidate halo stars, together with similar data for a further 14 known metal-poor subdwarfs. Those observations provide the first extensive dataset of RI photometry of metal-poor, main-sequence stars with well-determined trigonometric parallaxes. Finally, we have obtained intermediate-resolution optical spectroscopy of 175 stars. We are able to estimate abundances for 270 stars. 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.

arXiv commentto appear in Monthly Notices of the Royal Astronomical Society (some tables appear out of order in the text)

References in corpus (8)

• Discovery of a Supernova Explosion at Half the Age of the Universe and its Cosmological Implications
• The High-Z Supernova Search: Measuring Cosmic Deceleration and Global Cur vature of the Universe Using Type Ia Supernovae
• Abundances and Kinematics of Field Halo and Disk Stars I: Observational Data and Abundance Analysis
• Distances, ages, and epoch of formation of globular clusters
• M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale
• Ages of Globular Clusters from Hipparcos Parallaxes of Local Subdwarfs
• Tests of the Accelerating Universe with Near-Infrared Observations of a High-Redshift Type Ia Supernova
• Homogeneous photometry and metal abundances for a large sample of Hipparcos metal-poor stars

Cited by in corpus (13)

• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• Accurate fundamental parameters for Lower Main Sequence Stars
• The Solar Neighborhood XXXV: Distances to 1404 M Dwarf Systems Within 25 pc in the Southern Sky
• Sloan Low-Mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES): A Catalog of Very Wide, Low-mass Pairs
• The Subdwarf Luminosity Function
• A CCD Imaging Search for Wide Metal-Poor Binaries
• The outskirts of Cygnus OB2
• The Luminosity Function and Color-Magnitude Diagram of the Globular Cluster M12
• A search for cool subdwarfs: Stellar parameters for 134 candidates
• Meeting the Cool Neighbours, VI: A search for nearby ultracool dwarfs in the Galactic Plane
• VVVX near-IR photometry for 99 low-mass stars in the Gaia EDR3 Catalog of Nearby Stars
• The Distance to NGC 5904 (M 5) via the Subdwarfs Main Sequence Fitting Method
• Hidden Subluminous sd/wd among the FAUST UV sources toward OPHIUCHUS