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HD 24996


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Photopolarimetric activity and circumstellar environment of the young binary system DF Tau
We present the results of multi-year photometric and polarimetricobservations of the young binary system DF Tau in the UBVRI bands, aswell as bispectrum speckle interferometric observations in the H and Kbands obtained between 2001 and 2003. The photometric and polarimetricobservations suggest that the linear polarization of DF Tau does notdepend on its brightness, and the polarization variation has astochastic character. This result confirms earlier suggestions about thedominant role of hot accretion spots in the photometric activity of thisstar. We argue that the hot spots are at high latitudes and/or the starrotation axis is inclined to the line-of-sight. The influence ofcircumstellar (CS) dust on the variability is probably small since theinclination of the primary's CS disk to the line-of-sight is large.Using the total mass of the binary system DF Tau from Hartigan &Kenyon (2003, ApJ, 583, 334), we calculated new orbital parameters ofthe system. The new value of the orbital period (P = 74.1 yr) disagreeswith the photometric cycle of about 40 yr revealed by Lamzin et al.(2001b, A&A, 372, 922) from analysis of the historical light curveof this star. This suggests that this cycle is not caused by the orbitalmotions of the binary components, but probably reflects the cyclicalvariability of the global magnetic field on the main component.

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Osservazione e dati astrometrici

Costellazione:Toro
Ascensione retta:03h59m14.01s
Declinazione:+25°12'57.4"
Magnitudine apparente:8.284
Distanza:16666.667 parsec
Moto proprio RA:-2.3
Moto proprio Dec:-5.4
B-T magnitude:10.181
V-T magnitude:8.441

Cataloghi e designazioni:
Nomi esatti   (Edit)
HD 1989HD 24996
TYCHO-2 2000TYC 1817-940-1
USNO-A2.0USNO-A2 1125-01383992
HIPHIP 18629

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