Nonlinear, nonradial pulsation in rapidly oscillating AP stars

Details Nonlinear, nonradial pulsation in rapidly oscillating AP stars Nonlinear, nonradial pulsation in rapidly oscillating AP stars

Dec 1993

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993ap%26ss.210..207k&link_type=abstract

Astrophysics and Space Science (ISSN 0004-640X), vol. 210, no. 1-2, p. 207-214 (IAU Colloquium 134)

Astronomy and Astrophysics

Astrophysics

A Stars, Peculiar Stars, Spherical Harmonics, Stellar Oscillations, Stellar Rotation, Astrophysics, Light Curve, Nonlinearity, Radial Distribution

Scientific paper

The rapidly oscillating Ap stars pulsate in high-overtone, low degree p-modes with their pulsation axes aligned with their oblique magnetic axes. They show non-linearity in their pulsation in three ways: (1) The harmonics of the basic pulsation frequency are detectable. (2) The pulsation phase seems to vary stochastically on a time scale of days to years depending on the star. (3) The form of the nonradial surface distortion is not constant with time. These three effects are illustrated with HR 3831, the best studied of the roAp stars. HR 3831 pulsates in distored dipole mode which can be modelled as a linear sum of axisymmetric l = 0, 1, 2, and 3 spherical hamornics aligned with the magnetic axis. This gives rise to a 7-frequency multiplet split by exactly the rotation frequency. The form of the distortion shows small changes on a time-scale of years. HR 3831 shows a 5-frequency rotationally split first harmonic multiplet, a 3-frequency rotationally split second harmonic multiplet, and a single third harmonic frequency has probably been detected at an amplitude of 0.065 mmag. The first harmonic has changed its form significantly over the last 10 years. A technique for decomposing the fundamental frequency septuplet into its component spherical harmonics is used to fit the pulsation phase as a function of rotation phase. This allows a unique O-C to be defined for any length of light curve. The long term behavior of the O-C diagram cannot be modeled adequately with a combination of periodic (Doppler shift) and quadratic (evolution) terms; there seems to be a significant stochastic component.

Affiliated with

Also associated with

No associations

Rating

Nonlinear, nonradial pulsation in rapidly oscillating AP stars 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 Nonlinear, nonradial pulsation in rapidly oscillating AP stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonlinear, nonradial pulsation in rapidly oscillating AP stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-783897