δ Sct-type nature of the variable V2109 Cyg ^*,**

¹ Instituto de Astrofísica de Andalucía, CSIC, PO Box 3004, 18080 Granada, Spain
² Instituto de Astronomía, UNAM, PO Box 70-264, 4510 Mexico DF, Mexico
³ Observatoire de la Côte d'Azur, BP 4229, 0634 Nice Cedex 4, France

Corresponding author: E. Rodríguez, eloy@iaa.es

Received: 12 February 2003
Accepted: 12 June 2003

Abstract

We present the results of simultaneous photometry carried out from 1999 to 2001 of the variable V2109 Cyg together with a spectroscopic analysis based on one high resolution spectrum obtained in 2000. From this study, the star is definitively classified as an evolved δ Sct-type variable with solar metal abundances. This conclusion is also supported by the detected multiperiodic pulsational behaviour and the observed variation of the m₁ index over the pulsation cycle. This variation is slightly reversed relative to the V light curve, in very good agreement with the m₁ variation expected from the photometric calibrations. Besides the main frequency  cd^-1 and its first harmonic , a secondary peak is found at  cd^-1 () with f₁ identified as a radial mode and f₂ as non-radial. Whereas no significant variations are found in the amplitude of f₁ from season to season, the amplitude of f₂ changes strongly. Moreover, the main period has remained constant since 1990, within the observational uncertainties. Additional secondary frequencies may also be excited in this variable.