TY - JOUR
T1 - New BRITE-Constellation observations of the roAp star α Cir
AU - Weiss, W. W.
AU - Fröhlich, H. E.
AU - Kallinger, T.
AU - Kuschnig, R.
AU - Popowicz, A.
AU - Baade, D.
AU - Buzasi, D.
AU - Handler, G.
AU - Kochukhov, O.
AU - Koudelka, O.
AU - Moffat, A. F.J.
AU - Pablo, B.
AU - Wade, G.
AU - Zwintz, K.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - 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.
AB - 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.
KW - Space vehicles: instruments
KW - Stars: chemically peculiar
KW - Stars: individual: α Cir
KW - Stars: oscillations
KW - Stars: rotation
KW - Starspots
UR - http://www.scopus.com/inward/record.url?scp=85093975325&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202038345
DO - 10.1051/0004-6361/202038345
M3 - Article
AN - SCOPUS:85093975325
SN - 0004-6361
VL - 642
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A64
ER -