Surface imaging of stellar non-radial pulsations

Non - Radial Pulsations and Large - Scale Structure in Stellar Winds

Almost all early-type stars show Discrete Absorption Components (DACs) in their ultraviolet spectral lines. These can be attributed to Co-rotating Interaction Regions (CIRs): large-scale spiral-shaped structures that sweep through the stellar wind. We used the Zeus hydrodynamical code to model the CIRs. In the model, the CIRs are caused by " spots " on the stellar surface. Through the radiative...

An Adaptive Code for Radial Stellar Model Pulsations

We describe an implicit 1–D adaptive mesh hydrodynamics code that is specially tailored for radial stellar pulsations. In the Lagrangian limit the code reduces to the well tested Fraley scheme. The code has the useful feature that unwanted, long lasting transients can be avoided by smoothly switching on the adaptive mesh features starting from the Lagrangean code. Thus, a limit cycle pulsation ...

Aurigae: strong evidence for non-radial pulsations

We present further photometric observations of the unusual F0 V star 9 Aurigae and present evidence that this star’s radial velocity, spectroscopic line widths and line depths are also variable with the same frequencies as the photometric data (f1 ≈ 0.795 and f2 ≈ 0.345 d ). The phases of these sinusoids are stable over time scales of longer than one year, though the amplitudes can vary, making...

RADIATIVE OPACITIES AND STEllAR PULSATIONS

Synthetic photometry for non-radial pulsations in subdwarf B stars

We describe a method for computing theoretical photometric amplitude ratios for a number of modes of nonradially pulsating subdwarf B stars in both SDSS and UBVR systems. In order to avoid costly solutions of the non-adiabatic nonradial pulsation equations, we have adopted the adiabatic approximation. We argue that this is a valid approach, at least for the V361 Hya stars, because observations ...