Revisiting the pulsational characteristics of the exoplanet host star $\beta$ Pictoris

Abstract

Exoplanet properties crucially depend on their host stars' parameters. In case the exoplanet host star shows pulsations, asteroseismology can be used for an improved description of the stellar parameters. We aim to revisit the pulsational properties of beta Pic and identify its pulsation modes from normalised amplitudes in five different passbands. We also investigate the potential presence of a magnetic field. We conduct a frequency analysis using three seasons of BRITE-Constellation observations in the BRITE blue and red filters, the ~620-day long bRing light curve and the nearly 8-year long SMEI photometric time series. We calculate normalised amplitudes using all passbands including previously published values obtained from ASTEP observations. We investigate the magnetic properties of beta Pic using spectropolarimetric observations conducted with the HARPSpol instrument. Using 2D rotating models, we fit the normalised amplitudes and frequencies through Monte Carlo Markov Chains. We identify 15 pulsation frequencies in the range from 34 to 55c/d, where two display clear amplitude variability. We use the normalised amplitudes in up to five passbands to identify the modes as three l = 1, six l = 2 and six l = 3 modes. beta Pic is shown to be non-magnetic with an upper limit of the possible undetected dipolar field of 300G. Multiple fits to the frequencies and normalised amplitudes are obtained including one with a near equator-on inclination for beta Pic, which corresponds to our expectations based on the orbital inclination of beta Pic b and the orientation of the circumstellar disk. This solution leads to a rotation rate of 27% of the Keplerian break-up velocity, a radius of 1.497+-0.025Rsun, and a mass of 1.797+-0.035Msun. The ~2% errors in radius and mass do not account for uncertainties in the models and a potentially erroneous mode-identification.

26 pages, 19 figures, accepted in Astronomy & Astrophysics

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Cited by in corpus (21)

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• Direct confirmation of the radial-velocity planet $\beta$ Pic c
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• Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin-Orbit Misalignments are Common
• Exocomets size distribution in the $\beta$ Pictoris planetary system
• Spin-orbit alignment of the $\beta$ Pictoris planetary system
• New exocomets of $\beta$ Pic
• beta Cas: the first delta Scuti star with a dynamo magnetic field
• The $\beta$ Pictoris b Hill sphere transit campaign. Paper I: Photometric limits to dust and rings
• Polarization from Aligned Dust Grains in the $\beta$ Pic Debris Disk
• Magnetic chemically peculiar stars investigated by the Solar Mass Ejection Imager
• Space Photometry with BRITE-Constellation
• Multi-modal atmospheric characterization of $\beta$ Pictoris b: Adding high-resolution continuum spectra from GRAVITY
• Dynamical Mass Estimates of the $\beta$ Pictoris Planetary System Through Gaussian Process Stellar Activity Modelling
• Imaging of exocomets with infrared interferometry
• Asteroseismic Determination of Stellar Rotation: On Synchronization in the Close Eclipsing Binaries AB Cas and OO Dra
• Exocomet orbital distribution around $\beta$ Pictoris
• Discovery of carbon monoxide emission from five debris disks around young A-type stars
• The $\beta$ Pictoris b Hill sphere transit campaign. Paper II: Searching for the signatures of the $\beta$ Pictoris exoplanets through time delay analysis of the $\delta$ Scuti pulsations
• Direct Images of CO2 Absorption in the Atmosphere of a Super-Jupiter: Enhanced Metallicity Suggestive of Formation in a Disk
• Pulsation and Rotation of the EL CVn-type Eclipsing Binary 1SWASP J024743.37-251549.2