Line profile variations in classical Cepheids^*

Evidence for non-radial pulsations?

¹ Department of Astronomy and Astronomical Observatory of Odessa State University, Shevchenko Park, 65014, Odessa, Ukraine
² Isaac Newton Institute of Chile, Odessa Branch, Ukraine
³ Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7215, USA e-mail: luck@fafnir.astr.cwru.edu
⁴ Department of Astronomy, The University of Arizona, Tucson, AZ 85721, USA

Corresponding author: V. V. Kovtyukh, val@deneb.odessa.ua

Received: 30 July 2002
Accepted: 14 January 2003

Abstract

We have investigated line profiles in a large sample of Cepheid spectra, and found four stars that show unusual (for Cepheids) line profile structure (bumps or/and asymmetries). The profiles can be phase dependent but the behavior persists over many cycles. The asymmetries are unlikely to be due to the spectroscopic binarity of these stars or the specific velocity field in their atmospheres caused by shock waves. As a preliminary hypothesis, we suggest that the observed features on the line profiles in the spectra of X Sgr, V1334 Cyg, EV Sct and BG Cru can be caused by the non-radial oscillations. It is possible that these non-radial oscillations are connected to resonances between the radial modes (, or ).