2015/12/04 by R. Smolec · 43 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Cepheid variable #Convection #Galaxy #Hertzsprung–Russell diagram #High-pressure geophysics and materials #Instability #Instability strip #Luminosity #Mechanics #Overtone #Physics #RADIUS #Stars #Stellar evolution #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stv2868
published in Monthly Notices of the Royal Astronomical Society 456(4), 3475-3493 (Oxford University Press) · Accepted for publication in MNRAS
arxiv created 2015/12/04 · openalex publication_date 2016/01/14 · arxiv updated 2016/01/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a grid of non-linear convective type-II Cepheid models. The dense model grids are computed for 0.6 M⊙ and a range of metallicities ([Fe/H] = −2.0, −1.5, −1.0), and for 0.8 M⊙ ([Fe/H] = −1.5). Two sets of convective parameters are considered. The models cover the full temperature extent of the classical instability strip, but are limited in luminosity; for the most luminous models, violent pulsation leads to the decoupling of the outermost model shell. Hence, our survey reaches only the shortest period RV Tau domain. In the Hertzsprung–Russell diagram, we detect two domains in which period-doubled pulsation is possible. The first extends through the BL Her domain and low-luminosity W Vir domain (pulsation periods ∼2–6.5 d). The second domain extends at higher luminosities (W Vir domain; periods >9.5 d). Some models within these domains display period-4 pulsation. We also detect very narrow domains (∼10 K wide) in which modulation of pulsation is possible. Another interesting phenomenon we detect is double-mode pulsation in the fundamental mode and in the fourth radial overtone. Fourth overtone is a surface mode, trapped in the outer model layers. Single-mode pulsation in the fourth overtone is also possible on the hot side of the classical instability strip. The origin of the above phenomena is discussed. In particular, the role of resonances in driving different pulsation dynamics as well as in shaping the morphology of the radius variation curves is analysed.