Tidally perturbed pulsations in the pre-main sequence $\delta$ Scuti binary RS Cha

Abstract

Stellar components in binaries are subject to tidal forces which influence asteroseismic properties. Tidally pertubed pulsations have been reported for different objects but none of these are in their pre-main sequence phase of evolution. This makes RS Cha, consisting of two $\delta$ Scuti stars and with pulsational characteristics influenced by tidal effects , the first such object observed. We aim to investigate the pulsational properties of the eclipsing binary RS Cha in terms of the theory of tidally perturbed pulsations. Based on photometric time series obtained from the TESS satellite, we performed binary modelling using PHOEBE to interpret the binary light curve and to allow the investigation of the pulsations of both components in RS Cha. We modelled the detrended light curve with the superposition of linear modes. The frequencies were then interpreted as self excited modes perturbed by tidal forces. We find evidence for tidally perturbed modes, which enables the identification of pulsation modes. RS Cha mainly exhibits dipole modes, while one prominent $l=2$ or $l=3$ mode is also inferred. The latter verifies previous results from spectroscopic time series. This work shows that RS Cha is an ideal candidate to test the theory of tidally perturbed pulsations within the framework of asteroseismic modelling. The identification of multiple pulsation modes using this theory is unprecedented and will be a keystone in the future of pre-main sequence asteroseismology. However, amplitude modulation caused by the changing light ratio during the orbital phase in an eclipsing binary also plays a significant role, which can complicate mode identification.

11 pages plus 7 for the appendix, 8 pages plus 8 for the appendix, accepted for publication in Astronomy & Astrophysics

References in corpus (23)

• The NumPy array: a structure for efficient numerical computation
• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Physics Of Eclipsing Binaries. II. Towards the Increased Model Fidelity
• The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings
• Asteroseismology of solar-type stars
• The impact of companions on stellar evolution
• Heartbeat Stars, Tidally Excited Oscillations, and Resonance Locking
• The first view of $\delta$ Scuti and $\gamma$ Doradus stars with the TESS mission
• Very regular high-frequency pulsation modes in young intermediate-mass stars
• Asteroseismic masses, ages, and core properties of $\gamma$ Doradus stars using gravito-inertial dipole modes and spectroscopy
• Echography of young stars reveals their evolution
• The single-sided pulsator CO~Camelopardalis
• Seismic measurement of the locations of the base of convection zone and helium ionization zone for stars in the {\it Kepler} seismic LEGACY sample
• Discovery of $\beta$ Cep pulsations in the eclipsing binary V453 Cygni
• Tidally Trapped Pulsations in Binary Stars
• A Theoretical Study of Acoustic Glitches in Low-Mass Main-Sequence Stars
• Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha
• BRITE-Constellation photometry of $\bpi^5$ Orionis, an ellipsoidal SPB variable
• Calibration of the pre-main sequence RS Cha binary system
• Impact of the new solar abundances on the calibration of the PMS binary system RS Cha
• Characterization of Exoplanet-Host Stars

Cited by in corpus (2)

• Pulsational instability of pre-main sequence models from accreting protostars. I. Constraining the input physics for accretion with spectroscopic parameters and stellar pulsations
• A binary with a $\delta$~Scuti star and an oscillating red giant: orbit and asteroseismology of KIC9773821