Cool Stars 14 - Submitted Abstract # 70
This version created on 05 October 2006

Emission Line from Exotorus


Tsubasa Fukue, Kyoto University

Emission line profiles from an optically thin emitting torus in an
extrasolar system are investigated with model calculation under
various conditions.  The torus is assumed to be optically thin,
rigidly rotating.  When the rotational velocity of the torus is larger
than the thermal motion and the inclination angle is high, emission
lines have double peaks.  When the inclination angle is low, on the
other hand, emission lines do not have double peaks, but the intensity
is larger than that of near edge-on.  The companion can be detected
via the shadow within emission lines of the torus.  The dip owing to
the shadow can be periodically shifted as the companion orbits.  In
addition, the effect by the shadow of the companion resembles to the
Rossiter--McLaughlin effect.  When the density has non-axisymmetric
distribution and the line emitter is concentrated around the
companion, the emission line is periodically Doppler shifted as the
orbital phase of the companion.  Moreover, on additional dimming of a
line during transit, the transit time of the torus is longer than that
of the central object of the torus, and the peak of the transit effect
is different from that of the central object, because of the shape of
the torus.  The detection of a line which can not be interpreted as
comes from the central object or the companion may lead to the
detection of the exotorus.

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