C. P. Nicholls, P. R. Wood
Modelling ellipsoidal variables with known distances can lead to exact
determination of the masses of both components, even in the absence of
eclipses. We present such modelling using light and radial velocity curves of
ellipsoidal red giant binaries in the LMC, where they are also known as
sequence E stars. Stars were selected as likely eccentric systems on the basis
of light curve shape alone. We have confirmed their eccentric nature and
obtained system parameters using the Wilson-Devinney code. Most stars in our
sample exhibit unequal light maxima as well as minima, a phenomenon not
observed in sequence E variables with circular orbits. We find evidence that
the shape of the red giant changes throughout the orbit due to the high
eccentricity and the varying influence of the companion. Brief intervals of
pulsation are apparent in two of the red giants. We determine pulsation modes
and comment on their placement in the period-luminosity plane. Defining the
parameters of these systems paves the way for modelling to determine by what
mechanism eccentricity is maintained in evolved binaries.
View original:
http://arxiv.org/abs/1201.1043
No comments:
Post a Comment