The ability of intermediate-band Stromgren photometry to correctly identify dwarf, subgiant, and giant stars and provide stellar metallicities and surface gravities

Abstract

[Abridged] Several large scale photometric and spectroscopic surveys are being undertaken to provide a more detailed picture of the Milky Way. Given the necessity of generalisation in the determination of, e.g., stellar parameters when tens and hundred of thousands of stars are considered it remains important to provide independent, detailed studies to verify the methods used in the surveys. We evaluate available calibrations for deriving [M/H] from Stromgren photometry and develop the standard sequences for dwarf stars to reflect their metallicity dependence and test how well metallicities derived from ugriz photometry reproduce metallicities derived from the well-tested system of Stromgren photometry. We use a catalogue of dwarf stars with both Stromgren uvby photometry and spectroscopically determined iron abundances (in total 451 dwarf stars with 0.3<(b-y)_0<1.0). We also evaluate available calibrations that determine log g. A larger catalogue, in which metallicity is determined directly from uvby photometry, is used to trace metallicity-dependent standard sequences for dwarf stars. We derive new standard sequences in the c_1,0 versus (b-y)_0 plane and in the c_1,0 versus (v-y)_0 plane for dwarf stars with 0.40 < (b-y)_0 < 0.95 and 1.10 < (v-y)_0 < 2.38. We recommend the calibrations by Ramirez & Me'endez (2005) for deriving metallicities from Stromgren photometry and find that intermediate band photometry, such as Stromgren photometry, more accurately than broad band photometry reproduces spectroscopically determined [Fe/H]. Stromgren photometry is also better at differentiating between dwarf and giant stars. We conclude that additional investigations of the differences between metallicities derived from ugriz photometry and intermediate-band photometry, such as Stromgren photometry, are required.

Accepted for publication in A&A, 34 pages, including on-line material

References in corpus (10)

• alpha-, r-, and s-process element trends in the Galactic thin and thick disks
• The Milky Way Tomography with SDSS: II. Stellar Metallicity
• A common mass scale for satellite galaxies of the Milky Way
• The Geneva-Copenhagen Survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk
• The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic Globular and Open Clusters
• The Chemical Evolution of the Draco Dwarf Spheroidal Galaxy
• Stroemgren photometry of Galactic Globular Clusters. I. New Calibrations of the metallicity index
• The usage of Stromgren photometry in studies of Local Group Dwarf Spheroidal Galaxies - Application to Draco: a new catalogue of Draco members and a study of the metallicity distribution function and radial gradients
• Spatial Variations of Galaxy Number Counts in the Sloan Digital Sky Survey. II. Test of Galactic Extinction in High Extinction Regions
• The uvbyHbeta Metallicity Calibration for G and K Dwarfs

Cited by in corpus (1)

• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey