New BRITE-Constellation observations of the roAp star Alpha Circini

Abstract

Chemically peculiar (CP) stars with a measurable magnetic field comprise the group of mCP stars. The pulsating members define the subgroup of rapidly oscillating Ap (roAp) stars, of which Alpha Circini is the brightest member. Hence, Alpha Circini allows the application of challenging techniques, such as interferometry, very high temporal and spectral resolution photometry, and spectroscopy in a wide wavelength range, that have the potential to provide unique information about the structure and evolution of a star. Based on new photometry from BRITE-Constellation, obtained with blue and red filters, and on photometry from WIRE, SMEI, and TESS we attempt to determine the surface spot structure of Alpha Circini and investigate pulsation frequencies. We used photometric surface imaging and frequency analyses and Bayesian techniques in order to quantitatively compare the probability of different models. BRITE-Constellation photometry obtained from 2014 to 2016 is put in the context of space photometry obtained by WIRE, SMEI, and TESS. This provides improvements in the determination of the rotation period and surface features (three spots detected and a fourth one indicated). The main pulsation frequencies indicate two consecutive radial modes and one intermediate dipolar mode. Advantages and problems of the applied Bayesian technique are discussed.

arXiv comment11 pages, 8 figures, 5 tables

References in corpus (25)

• The Transiting Exoplanet Survey Satellite
• Validation of the new Hipparcos reduction
• MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics
• BRITE-Constellation: nanosatellites for precision photometry of bright stars
• A heuristic derivation of the uncertainty of the frequency determination in time series data
• Ap stars with resolved magnetically split lines: Magnetic field determinations from Stokes $I$ and $V$ spectra
• Measurements of magnetic fields over the pulsation cycle in six roAp stars with FORS1 at the VLT
• Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)
• The BRITE Constellation nanosatellite mission: Testing, commissioning and operations
• Triple system HD 201433 with a SPB star component seen by BRITE-Constellation: Pulsation, differential rotation, and angular momentum transfer
• Improved pulsating models of magnetic Ap stars I: exploring different magnetic field configurations
• Massive pulsating stars observed by BRITE-Constellation. I. The triple system Beta Centauri (Agena)
• Surface structure of the CoRoT CP2 target star HD 50773
• Theoretical light curves of dipole oscillations in roAp stars
• The fundamental parameters of the roAp star alpha Circini
• BRITE-Constellation: Data processing and photometry
• Modelling the light variability of the Ap star epsilon Ursae Majoris
• Asteroseismic analysis of the roAp star alpha Circini: 84 days of high-precision photometry from the WIRE satellite
• A self-consistent empirical model atmosphere, abundance and stratification analysis of the benchmark roAp star alpha Circini
• Oscillations in Beta UMi - Observations with SMEI
• Studying the photometric and spectroscopic variability of the magnetic hot supergiant $\zeta$ Orionis Aa
• Asteroseismology with the WIRE satellite
• A theoretical tool for the study of radial velocities in the atmospheres of roAp stars
• The roAp star $\alpha$ Circini as seen by BRITE-Constellation
• A new level of photometric precision: WIRE observations of eclipsing binary stars

Cited by in corpus (5)

• TESS Cycle 1 observations of roAp stars with 2-min cadence data
• Fundamental properties of a selected sample of Ap stars: Inferences from interferometric and asteroseismic constraints
• Magnetic chemically peculiar stars investigated by the Solar Mass Ejection Imager
• Space Photometry with BRITE-Constellation
• A case study of ACV variables discovered in the Zwicky Transient Facility survey