A system of standard stars for rotational velocity determinations

Abstract

Profiles for the He I X 4471, Mg II X 4481, and Fe I X 4476 lines were measured in the spectra of 217 bright northern and southern stars of types 09-F9, using photoelectric scans and photographic coudé spectrograms ob-tained at the Cerro Tololo Inter-American Observatory, Kitt Peak National Observatory, and Lowell Observato-ry. Half-intensity widths of the observed line profiles were compared with the corresponding quantities in a set of theoretical rotationally-broadened line profiles computed using the model-atmosphere approach. The resulting v sin fs are used to establish a system of standard rotational velocity stars, for use in estimating v sin i directly from visual inspection of spectrograms. An atlas of rotationally broadened spectra is presented, showing the effects of rotation on spectra of representative B-, A-, and F-type stars.