Updated pulsation models for anomalous Cepheids

¹ Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy
² Universita' Tor Vergata, via della Ricerca Scientifica 1, 00133 Roma, Italy e-mail: giuliana@mporzio.astro.it
³ Osservatorio Astronomico di Roma, Via di Frascati 33, 00040 Monteporzio Catone, Italy e-mail: caputo@coma.mporzio.astro.it

Corresponding author: M. Marconi, marcella@na.astro.it

Received: 11 August 2003
Accepted: 14 January 2004

Abstract

A theoretical investigation of the pulsation behavior of so-named “anomalous” Cepheids is presented. The study is based on nonlinear convective pulsation models with and 0.0004, mass in the range 1.3-2.2  and various luminosity levels. Based on these computations, we derive periods, bolometric light curves and the edges of the instability strip, showing that a variation of the metal abundance from to 0.0004 has quite small effects on these quantities. Then, using bolometric corrections and color-temperature transformations, we are able to provide the predicted relations connecting pulsational properties (periods, amplitudes) with magnitudes and colors in the various photometric bands. The theoretical pulsational scenario is compared to observed anomalous Cepheids in dwarf spheroidal galaxies and, in particular, the predicted mass-dependent Period-Magnitude-Amplitude and Period-Magnitude-Color relations are used to estimate individual mass values, as well as to discriminate between fundamental (F) and first-overtone (FO) pulsators.