A. V. Dodin, S. A. Lamzin, G. A. Chountonov
Results of longitudinal magnetic field B_z measurements for young star RW Aur
A are presented. We found that B_z in the formation region of HeI 5876 line's
narrow component varies from -1.47 \pm 0.15 kG to +1.10 \pm 0.15 kG. Our data
are consistent with a stellar rotational period of \simeq 5.6^d and with a
model of two hotspots with an opposite polarity of magnetic field and with a
difference in a longitude about 180^o. The spot with B_z<0 is located at the
hemisphere above the midplane of RW Aur's accretion disc and the spot with
B_z>0 is below the midplane. The following upper limits for B_z (at 3\sigma{}
level) were found after averaging of all our observations: 180 G for
photosperic lines, 220 G and 230 G for formation regions of H_\alpha{} and [OI]
6300 lines respectively. Upper limit 600 G were found in the region where broad
components of emisson lines form. For two cases out of 11 we observed the field
in a formation region of a blue absorption wing of NaI D lines i.e. in an
outflow: B_z= -180 \pm 50 G and -810 \pm 80 G. Radial velocity of RW Aur's
photospheric lines averaged over all our observations is about + 10.5 km/s what
is 5.5 km/s less than value derived ten years earlier by Petrov et al. (2001).
In this connection, we discuss a possibility that RW Aur is not a binary but a
triple system.
View original:
http://arxiv.org/abs/1111.2309
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