The Distribution of Europium over the Surface of 21 Com
Résumé
Comparison of optical high resolution high signal-to-noise ELODIE spectra of 21 Com taken in 2004 April and separated by about half of the 2 days rotational period, reveals variations of the Eu II resonance and low excitation lines between rotational phases 0.94 and 0.48. All Eu II lines are consistently stronger at phase 0.94. The synthesis of these Eu II lines yields disk-averaged estimates of the abundances of europium: about 50 times solar at phase 0.94 and 25 times solar at phase 0.48.