On the potassium-rotation connection in late-type Alpha Persei stars ^*

¹ Instituto de Astrofísica de Canarias, 38200 La Laguna, Spain e-mail: ege@iac.es
² University of Central Florida, Department of Physics, PO Box 162385, Orlando, FL 32816-2385, USA e-mail: ege@physics.ucf.edu
³ Centro Galileo Galilei, Apartado 565, 38700 Santa Cruz de La Palma, Spain e-mail: magazzu@tng.iac.es
⁴ Osservatorio Astrofisico de Arcetri, Largo Fermi 5, 50125 Firenze, Italy e-mail: randich@arcetri.astro.it
⁵ Laboratorio de Astrofísica Espacial y Física Fundamental, INTA, Apartado Postal 50727, 28080 Madrid, Spain e-mail: barrado@laeff.esa.es

Received: 9 July 2004
Accepted: 14 September 2004

Abstract

We present measurements of the line from spectra of 19 late-type members of the αPersei cluster obtained with the Intermediate Dispersion Spectrograph at the Isaac Newton Telescope. These stars span a narrow range of , from 5091 K to 4771 K, and a wide range of values (9 –170 ). For a given star, we find empirically that larger rotational broadening apparently increases the equivalent width of linearly for values from 15 to 75 . This correlation breaks down for 75 . After correction for this effect, we show that the potassium line equivalent widths do not really correlate with .