Publications of the MPIfR
Optical & Infrared
Interferometry Group
K.-D. Goecking, H.W. Duerbeck, T.
Plewa, J. Kaluzny, D. Schertl, G. Weigelt, and P. Flin
The W Ursae Majoris system ER Ori - a multiple
star
Astronomy and Astrophysics, v.289, p.287-836 (1994)
Abstract
308 photoelectric and 29 spectroscopic observations of the W-type W UMa
system ER Ori are presented and analyzed. A cross-correlation method
was
used to determine the radial velocity curves. The existence of a third
body was established by its presence in the cross-correlation function.
High-resolution speckle masking observations show that this companion
has a separation of 0.19 arcsec from the W UMa system, is about 2.3
magnitudes fainter than the binary at maximum light, and is very likely
physically connected to the system. The (O-C)-diagram of minimum times
was re-analyzed. The light time effect caused by the third body has
only
a marginal influence, indicating that its orbital plane has an
inclination close to 0 deg. The presence of the companion was taken
into
account inthe synthetic light and radial velocity curve study. This
combined solution yields a mass ratio of q = 0.64 +/- 0.08. The derived
masses and radii indicate that ER Ori is a slightly evolved W UMa
system.
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