Wilson-Bappu Effect: Extended to Surface Gravity

Abstract

Wilson and Bappu found a tight correlation between the stellar absolute visual magnitude (Mv) and the width of the Ca II K emission line for late-type stars in 1957. Here, we revisit the Wilson-Bappu relationship (hereafter, WBR) to claim that WBR can be an excellent indicator of stellar surface gravity of late-type stars as well as a distance indicator. We have measured the width (W) of the Ca II K emission line in high resolution spectra of 125 late-type stars, which were obtained with Bohyunsan Optical Echelle Spectrograph (BOES) and adopted from the UVES archive. Based on our measurement of the emission line width (W), we have obtained a WBR of Mv = 33.76 - 18.08 logW. In order to extend the WBR to be a surface gravity indicator, the stellar atmospheric parameters such as effective temperature (Teff), surface gravity (logg), metallicity ([Fe/H]), and micro-turbulence (${\xi }_{tur}$) have been derived from the self-consistent detailed analysis using the Kurucz stellar atmospheric model and the abundance analysis code, MOOG. Using these stellar parameters and logW, we found that logg = - 5.85 logW + 9.97 logTeff - 23.48 for late-type stars.

References in corpus (3)

• Stellar population models in the UV: I. Characterisation of the New Generation Stellar Library
• Tool for Automatic Measurement of Equivalent width (TAME)
• The [Fe/H] Dependence on the Ca {\sc ii}-$M_V$ Relationship

Cited by in corpus (6)

• Line-depth ratios as indicators of effective temperature and surface gravity
• The effect of surface gravity on line-depth ratios in the wavelength range 0.97-1.32 μm
• On the physical nature of the Wilson-Bappu effect: revising the gravity and temperature dependence
• An Updated Wing TiO Sensitive Index for Classification of M-Type Stars
• Correlating Intrinsic Stellar Parameters with Mg II Self-Reversal Depths
• Rubidium abundances in solar metallicity stars