Stellar Activity and the Stromgren Photometric Metallicity Calibration of Intermediate-Type Dwarf Stars

Abstract

We consider the effect of stellar activity, as measured by X-ray luminosity, on metallicities of Solar-neighborhood F and G dwarfs derived from Stromgren photometry. Rocha-Pinto & Maciel found evidence that Stromgren colors systematically underpredict [Fe/H] for stars with extremely high Ca II H & K emission. We investigate whether a recent photometric metallicity calibration derived by Martell & Laughlin might be subject to this effect, and whether the amount of underprediction could reliably be expressed as a function of log (L_X/L_bol). Among those calibration stars used by Martell & Laughlin which are also in the Bright Star Catalogue and detected in the ROSAT All-Sky Survey there is no evidence for a correlation between photometric metallicity and stellar activity. However, many of the "very active stars" on which the Rocha-Pinto & Maciel result was based are members of interacting binaries or are very young in age, and are not included in the X-ray sample that we are using. Among normal dwarf stars it appears that stellar activity has little effect on the metallicity calibration of Stromgren colors.

arXiv comment8 pages plus 10 figures, to appear in the October 2004 edition of PASP

References in corpus (4)

• Spectroscopic Properties of Cool Stars in the SDSS: An Analysis of Magnetic Activity and a Search for Subdwarfs
• Catalogue of [Fe/H] determinations for FGK stars : 2001 edition
• Metallicity effects on the chromospheric activity-age relation for late-type dwarfs
• An Improved uvby-Metallicity Calibration for Metal-Rich Stars

Cited by in corpus (3)

• The ability of intermediate-band Stromgren photometry to correctly identify dwarf, subgiant, and giant stars and provide stellar metallicities and surface gravities
• uvby-$\beta$ photometry of solar twins: the solar colors, model atmospheres, and the Teff and metallicity scales
• The Metallicity of Stars with Close Companions