On the effects of rotation on acoustic stellar pulsations: validity domains of perturbative methods and close frequency pairs

Abstract

Pulsation frequencies of acoustic modes are calculated for realistic rotating stellar models using both a perturbative and a two-dimensional approach. A comparison between the two yields validity domains which are similar to those previously obtained in Reese, Lignieres and Rieutord (2006) for polytropic models. One can also construct validity domains based on polynomial fits to the frequencies from the two-dimensional approach, and these also turn out to be similar, thus further confirming the agreement between the perturbative and two-dimensional approach at low rotation rates. Furthermore, as was previously shown in Espinosa, Perez Hernandez and Roca Cortes (2004), adjacent frequencies in multiplets come close together, thus forming pairs. This phenomena, exclusive to two-dimensional calculations, is shown to be an unlikely explanation of the close frequency pairs observed in delta Scuti stars. A systematic search for all close frequency pairs in the calculated spectrum is also carried out. The number of close frequency pairs is shown to agree with what is expected based on a Poisson distribution, but does not match the number or distribution of close pairs in stars like FG Vir. Furthermore, a lack of close frequency pairs appears at low rotation rates, where frequency multiplets do not overlap. Delta Scuti stars currently reported as having close frequency pairs do not fall in this interval.

9 pages, 7 figures, 2 tables, accepted for publication in MNRAS

References in corpus (12)

• ADIPLS -- the Aarhus adiabatic oscillation package
• ASTEC -- the Aarhus STellar Evolution Code
• Acoustic oscillations of rapidly rotating polytropic stars. II. Effects of the Coriolis and centrifugal accelerations
• Acoustic oscillations in rapidly rotating polytropic stars I. Effects of the centrifugal distortion
• The effect of rotation on the abundances of the chemical elements of the A-type stars in the Praesepe cluster
• On the Structure and Properties of Differentially Rotating Main-Sequence Stars in the 1-2 M_sun Range
• A new method for the spectroscopic identification of stellar non-radial pulsation modes. II. Mode identification of the Delta Scuti star FG Virginis
• Radial and Nonradial Oscillation Modes in Rapidly Rotating Stars
• The Kepler Asteroseismic Investigation: Scientific goals and the first results
• Amplitude variability or close frequencies in pulsating stars? The Delta Scuti star FG Vir
• On the interpretation of echelle diagrams for solar-like oscillations. Effect of centrifugal distortion
• Third Order Effect of Rotation on Stellar Oscillations of a $\beta$-Cephei Star

Cited by in corpus (3)

• Dealing With $\delta$-Scuti Variables: Transit Light Curve Analysis of Planets Orbiting Rapidly-Rotating, Seismically Active A/F Stars
• Regular frequency patterns in the classical delta Scuti star HD 144277 observed by the MOST satellite
• Stable higher order finite-difference schemes for stellar pulsation calculations