2016A&A...588A..54W


Query : 2016A&A...588A..54W

2016A&A...588A..54W - Astronomy and Astrophysics, volume 588A, 54-54 (2016/4-1)

The roAp star a Circinus as seen by BRITE-Constellation.

WEISS W.W., FROHLICH H.-E., PIGULSKI A., POPOWICZ A., HUBER D., KUSCHNIG R., MOFFAT A.F.J., MATTHEWS J.M., SAIO H., SCHWARZENBERG-CZERNY A., GRANT C.C., KOUDELKA O., LUFTINGER T., RUCINSKI S.M., WADE G.A., ALVES J., GUEDEL M., HANDLER G., MOCHNACKI S., ORLEANSKI P., PABLO B., PAMYATNYKH A., RAMIARAMANANTSOA T., ROWE J., WHITTAKER G., ZAWISTOWSKI T., ZOCLONSKA E. and ZWINTZ K.

Abstract (from CDS):

We report on an analysis of high-precision, multi-colour photometric observations of the rapidly-oscillating Ap (roAp) star α Cir. These observations were obtained with the BRITE-Constellation, which is a coordinated mission of five nanosatellites that collects continuous millimagnitude-precision photometry of dozens of bright stars for up to 180-days at a time in two colours (≃Johnson B and R). BRITE stands for BRight Target Explorer. The object α Cir is the brightest roAp star and an ideal target for such investigations, facilitating the determination of oscillation frequencies with high resolution. This star is bright enough for complementary interferometry and time-resolved spectroscopy. Four BRITE satellites observed α Cir for146d or 33 rotational cycles. Phasing the photometry according to the 4.4790d rotational period reveals qualitatively different light variations in the two photometric bands. The phased red-band photometry is in good agreement with previously-published WIRE data, showing a light curve symmetric about phase 0.5 with a strong contribution from the first harmonic. The phased blue-lband data, in contrast, show an essentially sinusoidal variation. We model both light curves with Bayesian Photometric Imaging, which suggests the presence of two large-scale, photometrically bright (relative to the surrounding photosphere) spots. We also examine the high-frequency pulsation spectrum as encoded in the BRITE photometry. Our analysis establishes the stability of the main pulsation frequency over the last ≃20yr, confirms the presence of frequency f7, which was not detected (or the mode not excited) prior to 2006, and excludes quadrupolar modes for the main pulsation frequency.

Abstract Copyright: © ESO, 2016

Journal keyword(s): stars: chemically peculiar - asteroseismology - stars: oscillations - stars: rotation - stars: individual: α Cir - starspots

VizieR on-line data: <Available at CDS (J/A+A/588/A54): alpcirb.dat alpcirr.dat>

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* SY Pic a2* 04 48 38.5185801286 -49 10 11.840224549   9.16 8.85     ApSrCrEu 43 0
2 V* V901 Ori Ro* 05 40 56.3704270929 -01 30 25.856714776 5.96 6.82 6.96     B2V 305 2
3 * tet Aur a2* 05 59 43.27012 +37 12 45.3047 2.36 2.54 2.62 2.62 2.68 A0VpSi 270 0
4 HD 50773 * 06 54 37.0338198405 -00 27 09.477956333   9.50 9.36     ApSr 23 0
5 V* V646 Mon a2* 07 03 47.5121927410 -01 05 58.710592411   8.92 8.90     ApSrEu 36 0
6 * eps UMa a2* 12 54 01.7495922 +55 57 35.362645 1.76 1.75 1.77 1.79 1.82 A1III-IVpkB9 461 0
7 * alf Cir a2* 14 42 30.4195804 -64 58 30.493451 3.55 3.43 3.19 2.96 2.86 A7VpSrCrEu 341 0

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2021.07.29-02:56:18

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