New BRITE-Constellation observations of the roAp star α Cir
| Autor: | A. F. J. Moffat, Oleg Kochukhov, B. Pablo, K. Zwintz, Gerald Handler, Werner W. Weiss, Adam Popowicz, H.-E. Fröhlich, Otto Koudelka, Rainer Kuschnig, T. Kallinger, Gregg A. Wade, D. Baade, Derek L. Buzasi |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
Rotation period 010504 meteorology & atmospheric sciences Astronomy and Astrophysics Astrophysics 01 natural sciences Magnetic field Photometry (optics) Stars Dipole Interferometry Space and Planetary Science 0103 physical sciences Spectral resolution Spectroscopy 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | Astronomy & Astrophysics. 642:A64 |
| ISSN: | 1432-0746 0004-6361 |
| DOI: | 10.1051/0004-6361/202038345 |
| Popis: | Context. 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 α Cir is the brightest member. Hence, α Cir 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. Aims. 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 α Cir and investigate pulsation frequencies. Methods. We used photometric surface imaging and frequency analyses and Bayesian techniques in order to quantitatively compare the probability of different models. Results. 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. |
| Databáze: | OpenAIRE |
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