Nonlinear Beat Cepheid and RR Lyrae Models
نویسنده
چکیده
The numerical hydrodynamic modelling of beat Cepheid behavior has been a long standing quest in which purely radiative models had failed consistently. We find that beat pulsations occur naturally when turbulent convection is accounted for in our hydrodynamics code. The development of a relaxation code and of a Floquet stability analysis greatly facilitates the search for and the analysis of beat Cepheid models. The conditions for the occurrence of beat behavior can be understood easily and at a fundamental level with the help of amplitude equations.
منابع مشابه
ar X iv : a st ro - p h / 99 09 02 4 v 1 1 S ep 1 99 9 Turbulent Convection in the Classical Variable Stars
We give a status report of convective Cepheid and RR Lyrae model pulsations. Some striking successes can be reported, despite the use of a rather simple treatment of turbulent convection with a 1D time-dependent diffusion equation for the turbulent energy. It is now possible to obtain stable double-mode (beat) pulsations in both Cepheid and RR Lyrae models with astrophysical parameters, i.e. pe...
متن کاملStellar Absolute Magnitudes via the Statistical Parallax Method
I review statistical parallax absolute magnitude determinations which employ data from the Hipparcos satellite for RR Lyrae and Cepheid variables, and for several other stellar classes. Five groups have studied the RR Lyrae stars, and the results are reassuringly consistent: MV (RR) = 0.77 ± 0.13 mag at [Fe/H] = –1.6 dex. Extensive Monte Carlo simulations showed that systematic errors are small...
متن کاملThe Light Curves of RR Lyrae Field Stars
Fourier decompositions have been made of the light curves of a large sample of RR Lyrae field stars. The coefficients have been tabulated. Following the scheme of an earlier investigation of classical Cepheids, certain combinations of the low-order coefficients+,, R,, , and -are plotted against period. The Bailey-type c pulsators stand out from the type ab stars, particularly on the R,, plot wh...
متن کاملThe Cepheid Instability Strip in the GAIA Era
We present recent results concerning distance determinations based on the two most popular primary distance indicators, namely classical Cepheids and RR Lyrae. We discuss the problems affecting the Cepheid distance scale, and in particular the dependence of fundamental Period-Luminosity (PL) and Period-Luminosity-Color (PLC) relations on the metal content. The key advantages in using the K-band...
متن کاملComparative Pulsation Calculations with Op and Opal Opacities
Comparative linear nonadiabatic pulsation calculations are presented using the OPAL and Opacity Project opacities. The two sets of opacities include effects due to intermediate coupling and fine structure as well as new abundances. We used two mass luminosity (M L) relations, one standard (BIT), and one employing substantial convective core overshoot (CO V). The two sets of opacities cannot be ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2001