2018A&A...611A..69B


Query : 2018A&A...611A..69B

2018A&A...611A..69B - Astronomy and Astrophysics, volume 611A, 69-69 (2018/3-1)

High-precision broad-band linear polarimetry of early-type binaries. II. Variable, phase-locked polarization in triple Algol-type system λ Tauri.

BERDYUGIN A., PIIROLA V., SAKANOI T., KAGITANI M. and YONEDA M.

Abstract (from CDS):

Aim. To study the binary geometry of the classic Algol-type triple system λ Tau, we have searched for polarization variations over the orbital cycle of the inner semi-detached binary, arising from light scattering in the circumstellar material formed from ongoing mass transfer. Phase-locked polarization curves provide an independent estimate for the inclination i, orientation Ω, and the direction of the rotation for the inner orbit.
Methods. Linear polarization measurements of λ Tau in the B, V, and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained on the 60 cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and Tohoku 60 cm (Haleakala, Hawaii, USA) remotely controlled telescopes over 69 observing nights. Analytic and numerical modelling codes are used to interpret the data.
Results. Optical polarimetry revealed small intrinsic polarization in λ Tau with ∼0.05% peak-to-peak variation over the orbital period of 3.95d. The variability pattern is typical for binary systems showing strong second harmonic of the orbital period. We apply a standard analytical method and our own light scattering models to derive parameters of the inner binary orbit from the fit to the observed variability of the normalized Stokes parameters. From the analytical method, the average for three passband values of orbit inclination i=76°+1–2 and orientation Ω=15°(195°)±2° are obtained. Scattering models give similar inclination values i=72-76° and orbit orientation ranging from Ω=16°(196°) to Ω=19°(199°), depending on the geometry of the scattering cloud. The rotation of the inner system, as seen on the plane of the sky, is clockwise. We have found that with the scattering model the best fit is obtained for the scattering cloud located between the primary and the secondary, near the inner Lagrangian point or along the Roche lobe surface of the secondary facing the primary. The inclination i, inferred from polarimetry, agrees with the previously made conclusion on the semi-detached nature of the inner binary, whose secondary component is filling its Roche lobe. The non-periodic scatter, which is also present in the polarization data, can be interpreted as being due to sporadic changes in the mass transfer rate.

Abstract Copyright: © ESO, 2017

Journal keyword(s): polarization - scattering - binaries: eclipsing - techniques: polarimetric - circumstellar matter

VizieR on-line data: <Available at CDS (J/A+A/611/A69): poldata.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 - 2022
#notes
1 * bet Per EB* 03 08 10.1324535 +40 57 20.328013 1.70 2.07 2.12 2.08 2.11 B8V 1183 1
2 * lam Tau EB* 04 00 40.8157175 +12 29 25.225937 2.66 3.29 3.41 3.44 3.53 B4IV 340 0
3 HD 25443 * 04 06 08.0655259656 +62 06 06.607649268 6.45 6.998 6.766     B0.5III 129 0
4 HD 48099 Be* 06 41 59.2308626256 +06 20 43.532571372 5.38 6.32 6.37 6.30 6.35 O5V((f))z+O9:V 285 0
5 HD 165052 SB* 18 05 10.5506592816 -24 23 54.847798080 6.16 6.98 6.87 7.77   O5.5:Vz+O8:V 257 1
6 * U Sge EB* 19 18 48.4082723376 +19 36 37.722978540 6.23 6.61 6.58     B7III+K1III 369 0
7 HD 204827 SB* 21 28 57.7592315784 +58 44 23.238427956 8.63 8.74 7.94 7.25 6.76 O9.5IV 328 0

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2022.08.10-19:51:54

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