Enhancement of wave transmissions in multiple radiative and convective zones

Cai, Tianlong; Yu, Cong; Wei, Xing

doi:10.1017/jfm.2021.178

Cited by 4 publications

(3 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, we also note that the present general formulation can be applied to study the transmission of progressive waves through layered media in stellar interiors or planetary atmospheres since it offers the possibility to easily retain and remove the boundary conditions according to the configuration. This can be useful in addressing the problem of the transport of angular momentum, heat, or chemical elements by waves in these objects and the present results provide a general formalism for tackling such issues (e.g., André et al 2019;Cai et al 2021) As shown by Takata (2016b), the reflection and transmission coefficients in a base wave transmission-reflection problem are related to those of the adjoint wave transmission-reflection problem (see Sect. 2.3 for a description of the two configurations).…”

Section: Concluding Remarks and Discussionmentioning

confidence: 69%

Multi-cavity gravito-acoustic modes in stars: A general analytical resonance condition

Pinçon,

Takata

2022

Preprint

View full text Add to dashboard Cite

Context. Over recent decades, asteroseismology has proven to be a powerful method for probing stellar interiors. Analytical descriptions of the global oscillation modes, in combination with pulsation codes, have provided valuable help in processing and interpreting the large amount of seismic data collected, for instance, by space-borne missions CoRoT, Kepler, and TESS. These prior results have paved the way to more in-depth analyses of the oscillation spectra of stars in order to delve into subtle properties of their interiors. This purpose conversely requires innovative theoretical descriptions of stellar oscillations. Aims. In this paper, we aim to analytically express the resonance condition of the adiabatic oscillation modes of spherical stars in a very general way that is applicable at different evolutionary stages. Methods. In the present formulation, a star is represented as an acoustic interferometer composed of a multitude of resonant cavities where waves can propagate and the short-wavelength JWKB approximation is met. Each cavity is separated from the adjacent ones by barriers, which corresponds to regions either where waves are evanescent or where the JWKB approximation fails. Each barrier is associated with a reflection and transmission coefficient. The stationary modes are then computed using two different physical representations: 1) studying the infinite-time reflections and transmissions of a wave energy ray through the ensemble of cavities or 2) solving the linear boundary value problem using the progressive matching of the wave function from one barrier to the adjacent one between the core and surface. Results. Both physical pictures provide the same resonance condition, which ultimately turns out to depend on a number of parameters: the reflection and transmission phase lags introduced by each barrier, the coupling factor associated with each barrier, and the wave number integral over each resonant cavity. Using such a formulation, we can retrieve, in a practical way, the usual forms derived in previous works in the case of mixed modes with two or three cavities coupled though evanescent barriers, low-and large-amplitude glitches, and the simultaneous presence of evanescent regions and glitches. Conclusions. The resonance condition obtained in this work provides a new tool that is useful in predicting the oscillation spectra of stars and interpret seismic observations at different evolutionary stages in a simple way. Practical applications require more detailed analyses to make the link between the reflection-transmission parameters and the internal structure. These aspects will be the subject of a future paper.

show abstract

Section: Concluding Remarks and Discussionmentioning

confidence: 69%

Multi-cavity gravito-acoustic modes in stars: A general analytical resonance condition

Pinçon,

Takata

2022

Preprint

View full text Add to dashboard Cite

show abstract

Section: Concluding Remarks and Discussionmentioning

confidence: 88%

Multi-cavity gravito-acoustic oscillation modes in stars

Pinçon

Takata²

2022

A&A

View full text Add to dashboard Cite

Context. Over recent decades, asteroseismology has proven to be a powerful method for probing stellar interiors. Analytical descriptions of the global oscillation modes, in combination with pulsation codes, have provided valuable help in processing and interpreting the large amount of seismic data collected, for instance, by space-borne missions CoRoT, Kepler, and TESS. These prior results have paved the way to more in-depth analyses of the oscillation spectra of stars in order to delve into subtle properties of their interiors. This purpose conversely requires innovative theoretical descriptions of stellar oscillations. Aims. In this paper, we aim to analytically express the resonance condition of the adiabatic oscillation modes of spherical stars in a very general way that is applicable at different evolutionary stages. Methods. In the present formulation, a star is represented as an acoustic interferometer composed of a multitude of resonant cavities where waves can propagate and the short-wavelength JWKB approximation is met. Each cavity is separated from the adjacent ones by barriers, which correspond to regions either where waves are evanescent or where the JWKB approximation fails. Each barrier is associated with a reflection and transmission coefficient. The stationary modes are then computed using two different physical representations: (1) studying the infinite-time reflections and transmissions of a wave energy ray through the ensemble of cavities or (2) solving the linear boundary value problem using the progressive matching of the wave function from one barrier to the adjacent one between the core and surface. Results. Both physical pictures provide the same resonance condition, which ultimately turns out to depend on a number of parameters: the reflection and transmission phase lags introduced by each barrier, the coupling factor associated with each barrier, and the wave number integral over each resonant cavity. Using such a formulation, we can retrieve, in a practical way, the usual forms derived in previous works in the case of mixed modes with two or three cavities coupled though evanescent barriers, low- and large-amplitude glitches, and the simultaneous presence of evanescent regions and glitches. Conclusions. The resonance condition obtained in this work provides a new tool that is useful in predicting the oscillation spectra of stars and interpreting seismic observations at different evolutionary stages in a simple way. Practical applications require more detailed analyses to make the link between the reflection-transmission parameters and the internal structure. These aspects will be the subject of a future paper.

show abstract

“…It has been noted in convectively coupled models, the non-traditional Coriolis terms have important effects on the widths and phases of the equatorial trapped waves (Fruman 2009;Roundy & Janiga 2012). Apart from these differences, traditional approximations were also found to have significant effect on wave frequency ranges (Cai et al 2021). In shallow water approximations, the depth of fluid is assumed to be much smaller the wavelength of perturbation.…”

Section: Introductionmentioning

confidence: 99%

Convectively coupled equatorial trapped waves in stars and planets

Cai,

Yu,

Wei

2021

Preprint

Self Cite

View full text Add to dashboard Cite

In this paper, we have studied the convectively coupled equatorially trapped waves in rotating stars, with and without magnetic field. The equatorial trapped HD and MHD Poincaré, Rossby, mixed Rossby-Poincaré, and Kelvin waves were identified. The effects of stratification and non-traditional Coriolis force terms have been investigated. When the flow is strongly stratified, the wave frequencies of the convectively coupled model are almost the same as those of shallow water model. However, when the flow is weakly stratified, the wave frequencies are constrained by the buoyancy frequency. The non-traditional Coriolis terms affect the widths and phases of the equatorial waves. The width increases with the increasing non-traditional Coriolis parameter. Phase shift occurs when the non-traditional Coriolis parameter is included. Magnetic effect is significant when the magnetic field is strong. We have applied the model in the solar atmosphere and solar tachocline to explain the Rieger type periodicities. For the solar atmosphere, when magnetic effect is taken into account, we find that the magnetic field should be smaller than 5G in the solar photosphere. Otherwise, the Rieger type periodicities can be only attributed to long Rossby waves. For the solar tachocline, we find that magnetic field of the solar tachocline should be smaller than 50kG to observe the 160 days Rieger period. In addition, we find that the effect of the non-traditional Coriolis terms is not obvious in the solar photosphere, but its effect on the tachocline is significant.

show abstract

Enhancement of wave transmissions in multiple radiative and convective zones

Abstract: Abstract

Cited by 4 publications

References 39 publications

Multi-cavity gravito-acoustic modes in stars: A general analytical resonance condition

Multi-cavity gravito-acoustic modes in stars: A general analytical resonance condition

Multi-cavity gravito-acoustic oscillation modes in stars

Convectively coupled equatorial trapped waves in stars and planets

Contact Info

Product

Resources

About