Tidally trapped pulsations in a close binary star system discovered by TESS

G. Handler; D. W. Kurtz; S. A. Rappaport; H. Saio; J. Fuller; D. Jones; Z. Guo; S. Chowdhury; P. Sowicka; F. Kahraman Aliçavuş; M. Streamer; S. J. Murphy; R. Gagliano; T. L. Jacobs; A. Vanderburg

doi:10.1038/s41550-020-1035-1

Tidally trapped pulsations in a close binary star system discovered by TESS

G. Handler^*, D. W. Kurtz, S. A. Rappaport, H. Saio, J. Fuller, D. Jones, Z. Guo, S. Chowdhury, P. Sowicka, F. Kahraman Aliçavuş, M. Streamer, S. J. Murphy, R. Gagliano, T. L. Jacobs, A. Vanderburg

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

48 Citations (Scopus)

Abstract

It has long been suspected that tidal forces in close binary stars could modify the orientation of the pulsation axis of the constituent stars. Such stars have been searched for, but until now never detected. Here we report the discovery of tidally trapped pulsations in the ellipsoidal variable HD 74423 in Transiting Exoplanet Survey Satellite (TESS) space photometry data. The system contains a δ Scuti pulsator in a 1.6 d orbit, whose pulsation mode amplitude is strongly modulated at the orbital frequency, which can be explained if the pulsations have a much larger amplitude in one hemisphere of the star. We interpret this as an obliquely pulsating distorted dipole oscillation with a pulsation axis aligned with the tidal axis. This is the first time that oblique pulsation along a tidal axis has been recognized. It is unclear whether the pulsations are trapped in the hemisphere directed towards the companion or in the side facing away from it, but future spectral measurements can provide the solution. In the meantime, the single-sided pulsator HD 74423 stands out as the prototype of a new class of obliquely pulsating stars in which the interactions of stellar pulsations and tidal distortion can be studied.

Original language	English
Pages (from-to)	684-689
Number of pages	6
Journal	Nature Astronomy
Volume	4
Issue number	7
DOIs	https://doi.org/10.1038/s41550-020-1035-1
Publication status	Published - 1 Jul 2020

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title = "Tidally trapped pulsations in a close binary star system discovered by TESS",

abstract = "It has long been suspected that tidal forces in close binary stars could modify the orientation of the pulsation axis of the constituent stars. Such stars have been searched for, but until now never detected. Here we report the discovery of tidally trapped pulsations in the ellipsoidal variable HD 74423 in Transiting Exoplanet Survey Satellite (TESS) space photometry data. The system contains a δ Scuti pulsator in a 1.6 d orbit, whose pulsation mode amplitude is strongly modulated at the orbital frequency, which can be explained if the pulsations have a much larger amplitude in one hemisphere of the star. We interpret this as an obliquely pulsating distorted dipole oscillation with a pulsation axis aligned with the tidal axis. This is the first time that oblique pulsation along a tidal axis has been recognized. It is unclear whether the pulsations are trapped in the hemisphere directed towards the companion or in the side facing away from it, but future spectral measurements can provide the solution. In the meantime, the single-sided pulsator HD 74423 stands out as the prototype of a new class of obliquely pulsating stars in which the interactions of stellar pulsations and tidal distortion can be studied.",

author = "G. Handler and Kurtz, {D. W.} and Rappaport, {S. A.} and H. Saio and J. Fuller and D. Jones and Z. Guo and S. Chowdhury and P. Sowicka and Ali{\c c}avu{\c s}, {F. Kahraman} and M. Streamer and Murphy, {S. J.} and R. Gagliano and Jacobs, {T. L.} and A. Vanderburg",

note = "Publisher Copyright: {\textcopyright} 2020, The Author(s), under exclusive licence to Springer Nature Limited.",

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T1 - Tidally trapped pulsations in a close binary star system discovered by TESS

AU - Handler, G.

AU - Kurtz, D. W.

AU - Rappaport, S. A.

AU - Saio, H.

AU - Fuller, J.

AU - Jones, D.

AU - Guo, Z.

AU - Chowdhury, S.

AU - Sowicka, P.

AU - Aliçavuş, F. Kahraman

AU - Streamer, M.

AU - Murphy, S. J.

AU - Gagliano, R.

AU - Jacobs, T. L.

AU - Vanderburg, A.

PY - 2020/7/1

Y1 - 2020/7/1

N2 - It has long been suspected that tidal forces in close binary stars could modify the orientation of the pulsation axis of the constituent stars. Such stars have been searched for, but until now never detected. Here we report the discovery of tidally trapped pulsations in the ellipsoidal variable HD 74423 in Transiting Exoplanet Survey Satellite (TESS) space photometry data. The system contains a δ Scuti pulsator in a 1.6 d orbit, whose pulsation mode amplitude is strongly modulated at the orbital frequency, which can be explained if the pulsations have a much larger amplitude in one hemisphere of the star. We interpret this as an obliquely pulsating distorted dipole oscillation with a pulsation axis aligned with the tidal axis. This is the first time that oblique pulsation along a tidal axis has been recognized. It is unclear whether the pulsations are trapped in the hemisphere directed towards the companion or in the side facing away from it, but future spectral measurements can provide the solution. In the meantime, the single-sided pulsator HD 74423 stands out as the prototype of a new class of obliquely pulsating stars in which the interactions of stellar pulsations and tidal distortion can be studied.

AB - It has long been suspected that tidal forces in close binary stars could modify the orientation of the pulsation axis of the constituent stars. Such stars have been searched for, but until now never detected. Here we report the discovery of tidally trapped pulsations in the ellipsoidal variable HD 74423 in Transiting Exoplanet Survey Satellite (TESS) space photometry data. The system contains a δ Scuti pulsator in a 1.6 d orbit, whose pulsation mode amplitude is strongly modulated at the orbital frequency, which can be explained if the pulsations have a much larger amplitude in one hemisphere of the star. We interpret this as an obliquely pulsating distorted dipole oscillation with a pulsation axis aligned with the tidal axis. This is the first time that oblique pulsation along a tidal axis has been recognized. It is unclear whether the pulsations are trapped in the hemisphere directed towards the companion or in the side facing away from it, but future spectral measurements can provide the solution. In the meantime, the single-sided pulsator HD 74423 stands out as the prototype of a new class of obliquely pulsating stars in which the interactions of stellar pulsations and tidal distortion can be studied.

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Tidally trapped pulsations in a close binary star system discovered by TESS

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