On the understanding of pulsations in the atmosphere of roAp stars: phase diversity and false nodes

Details On the understanding of pulsations in the atmosphere of roAp stars: phase diversity and false nodes On the understanding of pulsations in the atmosphere of roAp stars: phase diversity and false nodes

2011-03-02

arxiv.org/abs/1103.0473v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

21 pages, 25 figures

Scientific paper

Studies based on high-resolution spectroscopic data of rapidly oscillating Ap stars show a surprising diversity of pulsation behavior in the atmospheric layers, pointing, in particular, to the co-existence of running and standing waves. The correct interpretation of these data requires a careful modelling of pulsations in these magnetic stars. In light of this, in this work we present a theoretical analysis of pulsations in roAp stars, taking into account the direct influence of the magnetic field. We derive approximate analytical solutions for the displacement components parallel and perpendicular to the direction of the magnetic field, that are appropriate to the outermost layer. From these, we determine the expression for the theoretical radial velocity for an observer at a general position, and compute the corresponding pulsation amplitude and phase as function of height in the atmosphere. We show that the integral for the radial velocity has contributions from three different types of wave solutions, namely, running waves, evanescent waves, and standing waves of nearly constant amplitude. We then consider a number of case studies to illustrate the origin of the different pulsational behaviour that is found in the observations. Concerning pulsation amplitude, we find that it generally increases with atmospheric height. Pulsation phase, however, shows a diversity of behaviours, including phases that are constant, increasing, or decreasing with atmospheric height. Finally, we show that there are situations in which the pulsation amplitude goes through a zero, accompanied by a phase jumps of $\pi$, and argue that such behaviour does not correspond to a pulsation node in the outermost layers of the star, but rather to a visual effect, resulting from the observers inability to resolve the stellar surface.

Affiliated with

Also associated with

No associations

Rating

On the understanding of pulsations in the atmosphere of roAp stars: phase diversity and false nodes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with On the understanding of pulsations in the atmosphere of roAp stars: phase diversity and false nodes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the understanding of pulsations in the atmosphere of roAp stars: phase diversity and false nodes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-475021