A spectral study of Vega: A rapidly-rotating pole-on star

Abstract

Ultra-high signal-to-noise, high dispersion spectroscopy over the wavelength range \mbox{$\lambda 4487 - 4553$} shows Vega to be a rapidly rotating star $(V_{\rm eq}\sim 160\,{\rm km\,s^{-1}})$ seen almost pole-on. These data, analyzed anew, are combined with analyses of the hydrogen lines (${\rm H}\gamma, {\rm H}\beta$ and ${\rm H}\alpha$) and the latest absolute continuum flux for Vega to yield the following results: $V \sin i=21.9\pm 0.1\,{\rm km\,s^{-1}}$, polar $T_{\rm eff}=9680\pm 10\,{\rm K}$, polar $\log g=4.00\pm 0.02\,{\rm dex}$, $V_{\rm eq}=160\pm 10\,{\rm km\,s^{-1}}$, $\xi_{\rm T}=1.08\pm 0.02\,{\rm km\, s^{-1}}$ and $i=7.9\pm 0.5^{\circ}$. The variations in $T_{\rm eff}$ and $\log g$ over the photosphere total 350 K and 0.06 dex, respectively. The mean $T_{\rm eff}=9510\pm 10\,{\rm K}$ and mean $\log g=3.97\pm 0.02\,{\rm dex}$ agree with the spherical model values derived here and by others.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html